token-js: Support `InterestBearingMint` instructions

[joncinque]

Problem

token-2022 includes a new mint extension to set an interest rate for tokens, but it isn't supported in the JS bindings. The relevant top-level instruction definition can be found here:

solana-program-library/token/program-2022/src/instruction.rs

Line 591 in 056948b

InterestBearingMintExtension,

and the sub-instructions here:

solana-program-library/token/program-2022/src/extension/interest_bearing_mint/instruction.rs

Lines 18 to 57 in 056948b

	/// Interesting-bearing mint extension instructions
	#[derive(Clone, Copy, Debug, PartialEq, IntoPrimitive, TryFromPrimitive)]
	#[repr(u8)]
	pub enum InterestBearingMintInstruction {
	/// Initialize a new mint with interest accrual.
	///
	/// Fails if the mint has already been initialized, so must be called before
	/// `InitializeMint`.
	///
	/// The mint must have exactly enough space allocated for the base mint (82
	/// bytes), plus 83 bytes of padding, 1 byte reserved for the account type,
	/// then space required for this extension, plus any others.
	///
	/// Accounts expected by this instruction:
	///
	/// 0. `[writable]` The mint to initialize.
	///
	/// Data expected by this instruction:
	/// `crate::extension::interest_bearing::instruction::InitializeInstructionData`
	///
	Initialize,
	/// Update the interest rate. Only supported for mints that include the
	/// `InterestBearingConfig` extension.
	///
	/// Accounts expected by this instruction:
	///
	/// * Single authority
	/// 0. `[writable]` The mint.
	/// 1. `[signer]` The mint rate authority.
	///
	/// * Multisignature authority
	/// 0. `[writable]` The mint.
	/// 1. `[]` The mint's multisignature rate authority.
	/// 2. ..2+M `[signer]` M signer accounts.
	///
	/// Data expected by this instruction:
	/// `crate::extension::interest_bearing::BasisPoints`
	///
	UpdateRate,
	}

Solution

Following the model in #2951 , add support for these new instructions, state, and extension type, including some end-to-end tests.

This is the first step for support, since we also need a client-side way to convert from token amount to tokens + interest accrued.