feat: improve E-matching pattern inference in `grind` (#8196)

This PR improves the E-matching pattern inference procedure in `grind`.
Consider the following theorem:
```lean
@[grind →]
theorem eq_empty_of_append_eq_empty {xs ys : Array α} (h : xs ++ ys = #[]) : xs = #[] ∧ ys = #[] :=
  append_eq_empty_iff.mp h
```
Before this PR, `grind` inferred the following pattern:
```lean
@HAppend.hAppend _ _ _ _ #2 #1
```
Note that this pattern would match any `++` application, even if it had
nothing to do with arrays. With this PR, the inferred pattern becomes:
```lean
@HAppend.hAppend (Array #3) (Array _) (Array _) _ #2 #1
```
With the new pattern, the theorem will not be considered by `grind` for
goals that do not involve `Array`s.