Token JS: Use COptionPubkeyLayout for all COption fields

[buffalojoec]

After #6164, we now have a serialization layout for COption<Pubkey>, where a None value is represented by a single 0, while Some(Pubkey) is represented by a 1 plus the public key bytes.

There are a handful more instructions in Token2022 that use COption<Pubkey>. Here are a few examples:

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

Lines 474 to 482 in 8b22d75

	InitializeMint2 {
	/// Number of base 10 digits to the right of the decimal place.
	decimals: u8,
	/// The authority/multisignature to mint tokens.
	#[cfg_attr(feature = "serde-traits", serde(with = "As::<DisplayFromStr>"))]
	mint_authority: Pubkey,
	/// The freeze authority/multisignature of the mint.
	#[cfg_attr(feature = "serde-traits", serde(with = "coption_fromstr"))]
	freeze_authority: COption<Pubkey>,

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

Lines 549 to 553 in 8b22d75

	InitializeMintCloseAuthority {
	/// Authority that must sign the `CloseAccount` instruction on a mint
	#[cfg_attr(feature = "serde-traits", serde(with = "coption_fromstr"))]
	close_authority: COption<Pubkey>,
	},

Update their JavaScript instruction builders to use the new layout!

[qiweiii]

would like to work on this!