Add impl for TryFromIntError

[newAM]

This implements defmt::Format for TryFromIntError which enables code like this:

use core::convert::{TryFrom, TryInto};

let foo: u64 = u64::MAX;
let bar: u32 = defmt::unwrap!(foo.try_into());
let eggs: u32 = defmt::unwrap!(u32::try_from(foo));

When it fails it looks like this:

ERROR panicked at 'unwrap failed: foo.try_into()'
error: `TryFromIntError(())`

Which is similar to what it looks like on std targets with .unwrap()

thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: TryFromIntError(())', src/main.rs:5:35

[jonas-schievink]

Thanks!

bors r+

[bors]

Build succeeded:

• ci