Add support for getting contract IDs that would be assigned to deployments

[leighmcculloch]

We need to add support for getting contract IDs that would be assigned to deployments.

We have stub functions already in the code for this capability, but they aren't filled in because the host functions don't exist for them to work. For example:

rs-soroban-sdk/soroban-sdk/src/deploy.rs

Lines 113 to 117 in 5a6429c

	/// Return the ID of the contract defined by the deployer.
	#[doc(hidden)]
	pub fn id(&self) -> BytesN<32> {
	todo!()
	}

The reason to provide this functionality is two fold:

• So that in tests developers can pre-generate a contract ID that they expect will be used later in the test.
• So that contracts can store the contract ID of a contract given inputs.

Dependent on stellar/rs-soroban-env#538
Blocking stellar/soroban-examples#152

[anupsdf]

@leighmcculloch , Can this be closed now that we have get_contract_id host fn?

[leighmcculloch]

The host fn was implemented, but the sdk work to use it has not been completed, which is what this issue is for.

For example:

rs-soroban-sdk/soroban-sdk/src/deploy.rs

Lines 152 to 157 in f743d6f

	/// Return the address of the contract defined by the deployer.
	#[doc(hidden)]
	/// Returns what the address of the contract will be once deployed.
	pub fn deployed_address(&self) -> Address {
	todo!()
	}

rs-soroban-sdk/soroban-sdk/src/deploy.rs

Lines 184 to 188 in f743d6f

	/// Return the address of the contract defined by the deployer.
	#[doc(hidden)]
	pub fn contract_address(&self) -> Address {
	todo!()
	}

Also interesting note those two functions used to be named the same, and should still be named the same. Strange that one has been renamed without the other.

[leighmcculloch]

Closed by #1086