feat: overlapping match patterns in grind

[leodemoura]

This PR adds better support for overlapping match patterns in grind. grind can now solve examples such as

inductive S where
  | mk1 (n : Nat)
  | mk2 (n : Nat) (s : S)
  | mk3 (n : Bool)
  | mk4 (s1 s2 : S)

def f (x y : S) :=
  match x, y with
  | .mk1 _, _ => 2
  | _, .mk2 1 (.mk4 _ _) => 3
  | .mk3 _, _ => 4
  | _, _ => 5

example : b = .mk2 y1 y2 → y1 = 2 → a = .mk4 y3 y4 → f a b = 5 := by
  unfold f
  grind (splits := 0)

[leanprover-community-bot]

Mathlib CI status (docs):

• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase c54287fb0d2bd580bf3a9035581f89cf25d609c8 --onto f9e904af5022a57adb6105cda65d1569449346c2. (2025-01-21 21:32:04)