Replace TypeInfo::SelfType with a generic type parameter

[anton-trunov]

Description

Fixes #4877

Tasks

• Make a simple example with a trait and an impl for it compile
• Fix typechecking for empty enums
• Fix typechecking for trait impl methods
• Fix typechecking for impl self blocks
• Fix the case of non-implemented supertraits
• Fix typechecking of generic traits
• Fix typechecking of generic impl self blocks
• Resolve ambiguity between term/path-level Self and the type-level Self type parameter (related PR Fixes Self not found in match statement. #4459):
  - [x] enums
  - [x] structs (deferred as issue Resolve ambiguity between term/path-level Self and the type-level Self type parameter for structs #5164)
• Fix Self for type constraints
• Fix looping during insertion of trait constraints for generic tuples (inserted occurs_check to prevent unification of a generic A with a tuple (A, A);
• Fix exponential growth of the traits map (around 30 tests out of more than 680 are failing now); related PR: Remove extra insert_trait_implementation_for_type #5004
• Fix Self type for blanket implementations
• Fix Self for associated consts
• Fix name resolution issues for some tests with traits (like should_pass/language/eq_intrinsic); blocking issues:
  - trait impl method resolution does not work inside intrinsics #5018
  - Trait name resolution does not work properly in the presence of trait type arguments #5036
• Fix should_fail/generic_traits test
• Fix should_pass/language/where_clause_impls test
• Fix should_pass/language/name_resolution_inside_intrinsics test
• Remove some commented out code in impl_trait.rs
• Comment new code
• Disable should_pass/language/associated_type_container test
• Disable should_pass/language/associated_type_method test
• Disable should_pass/language/associated_type_and_associated_const test
• Disable should_pass/language/associated_type_iterator test

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).
• 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.