Fix reaction pickers UX in reactions sheet

[gpunto]

Goal

Couple of fixes:

• The chips on the message reactions sheet should work as filters, not as reaction toggles
• Update grid cell size for the extended reactions sheet so there's more breathing room

Implementation

Nothing special really, just direct impl of the fixes above

🎨 UI Changes

UI is mostly identical, just 1 fewer column on common devices. Visible in the new paparazzi snapshot

Testing

You can check both in the sample

[github-actions]

PR checklist ✅

All required conditions are satisfied:

• Title length is OK (or ignored by label).
• At least one pr: label exists.
• Sections ### Goal, ### Implementation, and ### Testing are filled.

🎉 Great job! This PR is ready for review.

[github-actions]

SDK Size Comparison 📏

SDK	Before	After	Difference	Status
stream-chat-android-client	5.25 MB	5.69 MB	0.44 MB	🟡
stream-chat-android-ui-components	10.60 MB	11.00 MB	0.40 MB	🟡
stream-chat-android-compose	12.81 MB	12.03 MB	-0.78 MB	🚀