Move `snapshots` and `breakpoint` functionality into a dedicated module

[Jaybsoni]

Context: Move the contents of ~/pennylane/debugging.py to a dedicated module and separated snapshots from PLDB and pldb.

[github-actions[bot]]

Hello. You may have forgotten to update the changelog! Please edit doc/releases/changelog-dev.md with:

• A one-to-two sentence description of the change. You may include a small working example for new features.
• A link back to this PR.
• Your name (or GitHub username) in the contributors section.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.67%. Comparing base (c6a7cb0) to head (4b62406). Report is 254 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #5845 +/- ## ========================================== - Coverage 99.67% 99.67% -0.01% ========================================== Files 418 420 +2 Lines 40080 39787 -293 ========================================== - Hits 39951 39657 -294 - Misses 129 130 +1 ```

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