To allow forcing a list on multiple lines based on the presence of a
trailing comma

- Strip trailing slashes from Forgejo/Gitea Hosts
- "Repository" and "View-Source" links do not include `//`

- Only emit `#Lx` instead of `#Lx-Lx` for single lines.

Use previous message when tail is followed by regular items

Now it's consistent with the way we print other error messages and
allows us greater control, like adding additional extra labels and such.

Now it can tell the difference when a pattern has the wrong arity and
refer to it as a "pattern" instead of a "call".

Added Warning::TopLevelDefinitionShadowsImport with tests and snapshots

This changes the behavior so that `import one/two.three` issues the typical
error, as `one/two` implies the user meant to use Gleam's import syntax,
and likely just made a typo.

Also fixes the whitespace for the error, which was found while examining the snapshot

The `.` is really the problem in this instance, and so it seems better to point to it as the problem as opposed to the identifier