Add master edition account deserialization to spl metadata

[kespinola]

Changes

• Include MasterEditionAccount to spl metadata to deserialize master edition v2 accounts

pub struct CreateDrop<'info> {
    /// authority over and payer for the drop
    #[account(mut)]
    pub authority: Signer<'info>,

    #[account(
        seeds = [state::PREFIX.as_bytes(), Metadata::id().as_ref(), metadata_mint.key().as_ref(), state::EDITION.as_bytes()],
        seeds::program = Metadata::id(),
        bump,
    )]

    #[account(constraint = master_edition.supply > 0)]
    pub master_edition: Account<'info, MasterEditionAccount>,
    
    ...
}

[vercel]

@kespinola is attempting to deploy a commit to the coral-xyz Team on Vercel.

A member of the Team first needs to authorize it.

[Henry-E]

Usually it's nice see an example or two implementing the new type but this looks ok and people will surely complain soon if it breaks. Thanks for the PR!

[kespinola]

@Henry-E updated PR description with usage example.

[Henry-E]

I meant more like an example we run inside the tests/ directory. It's kind of something that we're missing in general that we don't have a bunch of CPI examples in tests/spl. Someday