Fix accessibility warnings for missing tooltips/content

Zoey Ahmedrequested to merge
Zoey_Ahmed/gnome-calendar:fix-missing-tooltips into main

Please see commit messages for changes to each component.

Before/After

Month View

Before After
Screenshot_From_2026-01-02_15-48-30 Screenshot_From_2026-01-02_15-46-00

Quick Add/Calendar Rows

Before After
Screenshot_From_2026-01-02_15-51-45__Edit_ Screenshot_From_2026-01-02_20-03-23__Edit_

Date Chooser

Before After
Screenshot_From_2026-01-02_15-50-12__Edit_ Screenshot_From_2026-01-02_20-05-58__Edit_

Closes: #1522 (closed)

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