Add token related snippets

1. Init Mint account snippet  
 ```rust
 #[account(
        init,
        payer = ${payer},
        seeds = [${1}],
        bump,
        mint::decimals = ${2},
        mint::authority = ${payer},
        mint::freeze_authority = ${payer},  
    )]
    pub ntt_mint: Account<'info, Mint>,
```