This PR implements the following improvements to the `#grind_lint`
command:
1. More informative messages when the number of instances exceeds the
minimum threshold.
2. A code action for `#grind_lint inspect` that inserts
`set_option trace.grind.ematch.instance true` whenever the number of
instances exceeds
the minimum threshold.
3. Displaying doc strings for `grind` configuration options in
`#grind_lint`.
4. Improve doc strings for `#grind_lint inspect` and `#grind_lint
check`.
Example:
```lean
/--
info: instantiating `Array.filterMap_some` triggers more than 100 additional `grind` theorem instantiations
---
info: Array.filterMap_some
[thm] instances
[thm] Array.filterMap_filterMap ↦ 94
[thm] Array.size_filterMap_le ↦ 5
[thm] Array.filterMap_some ↦ 1
---
info: Try this to display the actual theorem instances:
[apply] set_option trace.grind.ematch.instance true in
#grind_lint inspect Array.filterMap_some
-/
#guard_msgs in
#grind_lint inspect Array.filterMap_some
```
46ff76aabd