Extract virtue

[VictorKoenders]

This PR extracts the derive framework from bincode-derive into its own crate. This crate is https://docs.rs/virtue.

Additionally fixes some minor issues

• src/impl_core.rs now has some clippy warnings. Because this code is copied from core I've just added a #![allow(clippy::needless_borrow)] at the top
• Clippy has a new warning to replace core::mem::replace(&mut self.slice, &mut []) with core::mem::take(&mut self.slice), so I've implemented that
• #![crate_type = "dylib"] is now deprecated, so I've removed it

[codecov-commenter]

Codecov Report

Merging #443 (038cdf7) into trunk (a067d1e) will increase coverage by 3.85%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##            trunk     #443      +/-   ##
==========================================
+ Coverage   63.12%   66.97%   +3.85%     
==========================================
  Files          46       35      -11     
  Lines        3479     2604     -875     
==========================================
- Hits         2196     1744     -452     
+ Misses       1283      860     -423     

Impacted Files	Coverage Δ
derive/src/derive_enum.rs	0.00% <0.00%> (ø)
derive/src/derive_struct.rs	0.00% <0.00%> (ø)
derive/src/lib.rs	0.00% <0.00%> (-5.34%)	⬇️
src/de/impl_core.rs	53.57% <ø> (ø)

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