Improve notification handling + clearing

[nkalupahana]

• [x] iOS
• [x] Android
• [x] Web
• [x] Code Review

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit 6142355):

• https://getbaselineapp--pr372-background-notificat-tpbmwy0x.web.app
• https://baseline-links--pr372-background-notificat-rm97z7g1.web.app

_{(expires Thu, 11 Jul 2024 17:43:13 GMT)}

_{🔥 via Firebase Hosting GitHub Action 🌎}

_{Sign: 6ef595205395a2b7f9e37612e0c468294c87d8eb}