Refactor sendFeedback utility and add ShareE2EEHistory command

[dozro]

Description

This pull request refactors the feedback mechanism for command execution in useCommands.ts by replacing multiple inline implementations of feedback messaging with a centralized sendFeedback utility function. This change improves code maintainability and consistency. Additionally, a new experimental command is introduced.

Command feedback refactoring:

• Replaced all inline sendFeedback implementations with calls to the shared sendFeedback utility function, standardizing feedback messages across commands and reducing code duplication. (src/app/hooks/useCommands.ts)

Code cleanup:

• Removed unnecessary imports such as MatrixEvent since feedback messaging is now handled by the utility function. (src/app/hooks/useCommands.ts)

New command addition:

• Added an experimental command ShareE2EEHistory to the Command enum. (src/app/hooks/useCommands.ts)

see matrix-org/matrix-spec-proposals#4268

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

[Just-Insane]

You mention /sharee2eehistory is experimental - is it gated behind an Experimental toggle? If not, it probably should be for now.

[dozro]

@Just-Insane

[Just-Insane]

LGTM! Once this gets some testing in, we can remove the gate.