IDL: Types with generics are not assignable to parameter of type Idl

[vadorovsky]

When upgrading Light Protocol to Anchor 0.29, I encountered the following error, when using the IDL const as Idl type:

       src/multisigParams.ts(140,40): error TS2345: Argument of type 'Multisig' is not assignable to parameter of type 'Idl'.
         Types of property 'accounts' are incompatible.
           Type '[{ name: "eventMerkleTree"; type: { kind: "struct"; fields: [{ name: "merkleTreeNr"; type: "u64"; }, { name: "newest"; type: "u8"; }, { name: "padding"; type: { array: ["u8", 7]; }; }, { name: "merkleTree"; type: { ...; }; }]; }; }, { ...; }, { ...; }]' is not assignable to type 'IdlAccountDef[]'.
             Type '{ name: "eventMerkleTree"; type: { kind: "struct"; fields: [{ name: "merkleTreeNr"; type: "u64"; }, { name: "newest"; type: "u8"; }, { name: "padding"; type: { array: ["u8", 7]; }; }, { name: "merkleTree"; type: { ...; }; }]; }; } | { ...; } | { ...; }' is not assignable to type 'IdlAccountDef'.
               Type '{ name: "eventMerkleTree"; type: { kind: "struct"; fields: [{ name: "merkleTreeNr"; type: "u64"; }, { name: "newest"; type: "u8"; }, { name: "padding"; type: { array: ["u8", 7]; }; }, { name: "merkleTree"; type: { ...; }; }]; }; }' is not assignable to type 'IdlAccountDef'.
                 The types of 'type.fields' are incompatible between these types.
                   Type '[{ name: "merkleTreeNr"; type: "u64"; }, { name: "newest"; type: "u8"; }, { name: "padding"; type: { array: ["u8", 7]; }; }, { name: "merkleTree"; type: { definedWithTypeArgs: { name: "MerkleTreeSha256"; args: [...]; }; }; }]' is not assignable to type 'IdlTypeDefStruct'.
                     Type '{ name: "merkleTreeNr"; type: "u64"; } | { name: "newest"; type: "u8"; } | { name: "padding"; type: { array: ["u8", 7]; }; } | { name: "merkleTree"; type: { definedWithTypeArgs: { name: "MerkleTreeSha256"; args: [...]; }; }; }' is not assignable to type 'IdlField'.
                       Type '{ name: "merkleTree"; type: { definedWithTypeArgs: { name: "MerkleTreeSha256"; args: [{ value: "18"; }, { value: "20"; }]; }; }; }' is not assignable to type 'IdlField'.
                         Types of property 'type' are incompatible.
                           Type '{ definedWithTypeArgs: { name: "MerkleTreeSha256"; args: [{ value: "18"; }, { value: "20"; }]; }; }' is not assignable to type 'IdlType'.
       src/multisigParams.ts(145,40): error TS2345: Argument of type 'Multisig' is not assignable to parameter of type 'Idl'.
       src/transaction.ts(35,42): error TS2345: Argument of type 'Multisig' is not assignable to parameter of type 'Idl'.
       src/transaction.ts(40,42): error TS2345: Argument of type 'Multisig' is not assignable to parameter of type 'Idl'.
       src/client.ts(51,21): error TS2344: Type 'Multisig' does not satisfy the constraint 'Idl'.
       src/client.ts(77,5): error TS2322: Type 'Program<Idl>' is not assignable to type 'Program<Multisig>'.
         Types of property 'account' are incompatible.
           Type 'AccountNamespace<Idl>' is missing the following properties from type 'AccountNamespace<Multisig>': transactionMerkleTree, eventMerkleTree, verifierState10Ins
       src/client.ts(77,33): error TS2345: Argument of type 'Multisig' is not assignable to parameter of type 'Idl'.
       src/client.ts(212,9): error TS2322: Type 'Multisig' is not assignable to type 'Idl'.
         Types of property 'accounts' are incompatible.
           Type '[{ name: "eventMerkleTree"; type: { kind: "struct"; fields: [{ name: "merkleTreeNr"; type: "u64"; }, { name: "newest"; type: "u8"; }, { name: "padding"; type: { array: ["u8", 7]; }; }, { name: "merkleTree"; type: { ...; }; }]; }; }, { ...; }, { ...; }]' is not assignable to type 'IdlAccountDef[]'.
             Type '{ name: "eventMerkleTree"; type: { kind: "struct"; fields: [{ name: "merkleTreeNr"; type: "u64"; }, { name: "newest"; type: "u8"; }, { name: "padding"; type: { array: ["u8", 7]; }; }, { name: "merkleTree"; type: { ...; }; }]; }; } | { ...; } | { ...; }' is not assignable to type 'IdlAccountDef'.
               Type '{ name: "eventMerkleTree"; type: { kind: "struct"; fields: [{ name: "merkleTreeNr"; type: "u64"; }, { name: "newest"; type: "u8"; }, { name: "padding"; type: { array: ["u8", 7]; }; }, { name: "merkleTree"; type: { ...; }; }]; }; }' is not assignable to type 'IdlAccountDef'.
                 The types of 'type.fields' are incompatible between these types.
                   Type '[{ name: "merkleTreeNr"; type: "u64"; }, { name: "newest"; type: "u8"; }, { name: "padding"; type: { array: ["u8", 7]; }; }, { name: "merkleTree"; type: { definedWithTypeArgs: { name: "MerkleTreeSha256"; args: [...]; }; }; }]' is not assignable to type 'IdlTypeDefStruct'.
                     Type '{ name: "merkleTreeNr"; type: "u64"; } | { name: "newest"; type: "u8"; } | { name: "padding"; type: { array: ["u8", 7]; }; } | { name: "merkleTree"; type: { definedWithTypeArgs: { name: "MerkleTreeSha256"; args: [...]; }; }; }' is not assignable to type 'IdlField'.
                       Type '{ name: "merkleTree"; type: { definedWithTypeArgs: { name: "MerkleTreeSha256"; args: [{ value: "18"; }, { value: "20"; }]; }; }; }' is not assignable to type 'IdlField'.
                         Types of property 'type' are incompatible.
                           Type '{ definedWithTypeArgs: { name: "MerkleTreeSha256"; args: [{ value: "18"; }, { value: "20"; }]; }; }' is not assignable to type 'IdlType'.
       src/client.ts(223,9): error TS2322: Type 'Multisig' is not assignable to type 'Idl'.
       src/multisig.ts(65,50): error TS2345: Argument of type 'Multisig' is not assignable to parameter of type 'Idl'.
        ELIFECYCLE  Command failed with exit code 1.

The reason is that the following IDL types from Rust, introduced in #2011:

anchor/lang/syn/src/idl/types.rs

Lines 210 to 215 in 7e5bdce

	GenericLenArray(Box<IdlType>, String),
	Generic(String),
	DefinedWithTypeArgs {
	name: String,
	args: Vec<IdlDefinedTypeArg>,
	},

are missing in ts/packages/anchor/src/idl.ts

[acheroncrypto]

Fixed by #2824.