refactor: extra files logic

[klkvr]

Resolves https://github.com/foundry-rs/foundry/issues/6241

Removes write_extra logic from ArtifactOutput trait Adds new methods:

• handle_artifacts - by default empty implementation which can be overloaded to implement handling of compiled artifacts. ConfigurableArtifacts implements it to write extra files
• is_dirty - method allowing ArtifactOutput implementations to reject cached artifacts and enforce recompilation. Used by ConfigurableArtifacts to reject artifacts which data is not enough to write required extra output files.
• handle_cached_artifacts - same as handle_artifacts but for those which were not recompiled. Used by ConfigurableArtifacts to write extra files from cached artifacts.

[holic]

thank you!

curious if this also resolves the issue in this comment: https://github.com/foundry-rs/foundry/issues/6241#issuecomment-1802142594

happy to open a new issue if not