Improved trait coherence checking

[tritao]

Description

This PR implements improved trait coherence checking,

The idea of trait coherence is that, given a trait and some set of types for its type parameters, there should be exactly one impl that applies.

To check for coherence, the compiler does two separate but related checks:

• orphan check - ensures that each impl abides by the orphan rules
• overlap check - ensures that no two impls overlap

Right now this implements overlap checks for traits and inherent impls, without yet taking into account for trait constraints.

Checklist

• I have linked to any relevant issues.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation where relevant (API docs, the reference, and the Sway book).
  • If my change requires substantial documentation changes, I have requested support from the DevRel team
• I have added tests that prove my fix is effective or that my feature works.
• I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• I have requested a review from the relevant team or maintainers.