Many of the types had very generic names (e.g. `Configuration`), and as
the types are now exported from `@keymanapp/common-types`, this was
unhelpful.
For units with many references, I used TypeScript's import-equals to
reduce the change impact. For units with only a few references, I added
the `LexicalModelTypes.` prefix to the references in source.
(Best reference I could find for import-equals: b722fa4e49)
Fixes: #12516
This change renames the test files for Web according to the discussion at
the Keyman conference in November 2024. It also renames some folders from
`test` to `tests`.
