This PR migrates most remaining tests to the new test suite. It also
completes the migration of directories like `tests/lean/run`, meaning
that PRs trying to add tests to those old directories will now fail.
This PR significantly improves the test coverage of the language server,
providing at least a single basic test for every request that is used by
the client. It also implements infrastructure for testing all of these
requests, e.g. the ability to run interactive tests in a project context
and refactors the interactive test runner to be more maintainable.
Finally, it also fixes a small bug with the recently implemented unknown
identifier code actions for auto-implicits (#10442) that was discovered
in testing, where the "import all unambiguous unknown identifiers" code
action didn't work correctly on auto-implicit identifiers.
Extends Lean's incremental reporting and reuse between commands into
various steps inside declarations:
* headers and bodies of each (mutual) definition/theorem
* `theorem ... := by` for each contained tactic step, including
recursively inside supported combinators currently consisting of
* `·` (cdot), `case`, `next`
* `induction`, `cases`
* macros such as `next` unfolding to the above

*Incremental reuse* means not recomputing any such steps if they are not
affected by a document change. *Incremental reporting* includes the
parts seen in the recording above: the progress bar and messages. Other
language server features such as hover etc. are *not yet* supported
incrementally, i.e. they are shown only when the declaration has been
fully processed as before.
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Co-authored-by: Scott Morrison <scott.morrison@gmail.com>