Support "wrapped" structs

[jarry-xiao]

#[derive(Debug, Clone, Copy, BorshDeserialize, BorshSerialize)]
#[repr(transparent)]
pub struct Foo(pub u64);

Will not get picked up by shank, but this will:

#[derive(Debug, Clone, Copy, BorshDeserialize, BorshSerialize)]
#[repr(transparent)]
pub struct Foo {
    x: u64,
}

Feels like there shouldn't be much of a difference