Add clippy rules to better align with `#[no_std]`

I suggest the rules at:
https://rust-lang.github.io/rust-clippy/master/index.html?groups=restriction&search=instead_of

ATM it shows the following rules:
- `clippy::alloc_instead_of_core`
- `clippy::std_instead_of_alloc`
- `clippy::std_instead_of_core`

