feat: Support providing custom keyring for keystore. (#12453)

## Description

Closes: #12438



---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [X] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [X] added `!` to the type prefix if API or client breaking change
- [x] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#pr-targeting))
- [x] provided a link to the relevant issue or specification
- [x] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/main/docs/building-modules)
- [x] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#testing)
- [x] added a changelog entry to `CHANGELOG.md`
- [x] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [x] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

CHANGELOG.md

@@ -52,6 +52,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * [#12089](https://github.com/cosmos/cosmos-sdk/pull/12089) Mark the `TipDecorator` as beta, don't include it in simapp by default.
 * [#12153](https://github.com/cosmos/cosmos-sdk/pull/12153) Add a new `NewSimulationManagerFromAppModules` constructor, to simplify simulation wiring.
 * [#12187](https://github.com/cosmos/cosmos-sdk/pull/12187) Add batch operation for x/nft module.
+* [#12453](https://github.com/cosmos/cosmos-sdk/pull/12453) Add `NewInMemoryWithKeyring` function which allows the creation of in memory `keystore` instances with a specified set of existing items.
 
 ### State Machine Breaking
 

crypto/keyring/keyring.go

@@ -150,7 +150,13 @@ type Options struct {
 // purposes and on-the-fly key generation.
 // Keybase options can be applied when generating this new Keybase.
 func NewInMemory(cdc codec.Codec, opts ...Option) Keyring {
-	return newKeystore(keyring.NewArrayKeyring(nil), cdc, BackendMemory, opts...)
+	return NewInMemoryWithKeyring(keyring.NewArrayKeyring(nil), cdc, opts...)
+}
+
+// NewInMemoryWithKeyring returns an in memory keyring using the specified keyring.Keyring
+// as the backing keyring.
+func NewInMemoryWithKeyring(kr keyring.Keyring, cdc codec.Codec, opts ...Option) Keyring {
+	return newKeystore(kr, cdc, BackendMemory, opts...)
 }
 
 // New creates a new instance of a keyring.

crypto/keyring/keyring_test.go

@@ -21,6 +21,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/crypto/keys/multisig"
 	"github.com/cosmos/cosmos-sdk/crypto/keys/secp256k1"
 	"github.com/cosmos/cosmos-sdk/crypto/types"
+	cryptotypes "github.com/cosmos/cosmos-sdk/crypto/types"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
@@ -455,6 +456,49 @@ func TestInMemoryLanguage(t *testing.T) {
 	require.Equal(t, "unsupported language: only english is supported", err.Error())
 }
 
+func TestInMemoryWithKeyring(t *testing.T) {
+	priv := cryptotypes.PrivKey(secp256k1.GenPrivKey())
+	pub := priv.PubKey()
+
+	cdc := getCodec()
+	_, err := NewLocalRecord("test record", priv, pub)
+
+	multi := multisig.NewLegacyAminoPubKey(
+		1, []cryptotypes.PubKey{
+			pub,
+		},
+	)
+
+	appName := "test-app"
+
+	legacyMultiInfo, err := NewLegacyMultiInfo(appName, multi)
+	require.NoError(t, err)
+	serializedLegacyMultiInfo := MarshalInfo(legacyMultiInfo)
+
+	kb := NewInMemoryWithKeyring(keyring.NewArrayKeyring([]keyring.Item{
+		{
+			Key:         appName + ".info",
+			Data:        serializedLegacyMultiInfo,
+			Description: "test description",
+		},
+	}), cdc)
+
+	t.Run("key exists", func(t *testing.T) {
+		_, err := kb.Key(appName)
+		require.NoError(t, err)
+	})
+
+	t.Run("key deleted", func(t *testing.T) {
+		err := kb.Delete(appName)
+		require.NoError(t, err)
+
+		t.Run("key is gone", func(t *testing.T) {
+			_, err := kb.Key(appName)
+			require.Error(t, err)
+		})
+	})
+}
+
 func TestInMemoryCreateMultisig(t *testing.T) {
 	cdc := getCodec()
 	kb, err := New("keybasename", "memory", "", nil, cdc)