chore: deprecate Lean.HashMap and Lean.HashSet

[TwoFX]

This restores all of the imports of Lean.Data.HashMap and Lean.Data.HashSet so that users actually see the deprecation warnings instead of a "declaration not found" error.

[ghost]

Mathlib CI status (docs):

• ❗ Batteries CI can not be attempted yet, as the nightly-testing-2024-08-08 tag does not exist there yet. We will retry when you push more commits. If you rebase your branch onto nightly-with-mathlib, Batteries CI should run now. (2024-08-08 09:58:06)
• ❗ Mathlib CI can not be attempted yet, as the nightly-testing-2024-08-08 tag does not exist there yet. We will retry when you push more commits. If you rebase your branch onto nightly-with-mathlib, Mathlib CI should run now. (2024-08-08 12:46:55)