feat(pointing): Release pressed keys on disconnect

[petejohanson]

Match the behavior for key press release on split peripheral disconnect, and track pressed input keys to release them as needed on disconnect.

PR check-list

• Branch has a clean commit history
• Additional tests are included, if changing behaviors/core code that is testable.
• Proper Copyright + License headers added to applicable files (Generally, we stick to "The ZMK Contributors" for copyrights to help avoid churn when files get edited)
• Pre-commit used to check formatting of files, commit messages, etc.