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.
This PR modifies the pretty printing of pi types. Now `∀` will be
preferred over `→` for propositions if the domain is not a proposition.
For example, `∀ (n : Nat), True` pretty prints as `∀ (n : Nat), True`
rather than as `Nat → True`. There is also now an option `pp.foralls`
(default true) that when false disables using `∀` at all, for
pedagogical purposes. This PR also adjusts instance implicit binder
pretty printing — nondependent pi types won't show the instance binder
name. Closes#1834.
The linked RFC also suggests using `_` for binder names in case of
non-dependance. We're tabling that idea. Potentially it is useful for
hygienic names; this could improve how `Nat → True` pretty prints as `∀
(a : Nat), True`, with this `a` that's chosen by implication notation
elaboration. Relatedly, this PR exposes even further the issue where
binder names are reused in a confusing way. Consider: `Nat → Nat → (a :
Nat) → a = a` pretty prints as `∀ (a a a : Nat), a = a`.
