Exporting types named the same as the module where they are defined in `Main` modules of library components may lead to accidental name conflicts. This became apparent when trying to access `Problem_Behavior` module via a fully qualified name and the compiler rejected it. This is due to the fact that `Main` module exported `Error` type defined in `Standard.Base.Error` module, thus making it impossible to access any other submodules of `Standard.Base.Error` via a fully qualified name.
This change adds a warning to FullyQualifiedNames pass that detects any such future problems.
While only `Error` module was affected, it was widely used in the stdlib, hence the number of changes.
Closes#5902.
# Important Notes
I left out the potential conflict in micro-distribution, thus ensuring we actually detect and report the warning.
Add `Test.with_clue` function similar to ScalaTest's [with_clue](https://www.scalatest.org/user_guide/using_assertions).
This is useful for tests where the assertion depends on context which is not clear from it's operands.
### Important Notes
Using with_clue changes `State Clue` which is extracted by the `fail` function.
The State is introduced by `Test.specify` when the test is not pending.
There should be no changes to the public API apart form the addition of `Test.with_clue`.
