Fix: File Gallery does not re-render after deleting a file

[DammyCodes-all]

Brief Title

Acceptance Criteria fulfillment

• Deleting a file from the File Gallery immediately removes it from the list without requiring a page reload.
• The delete confirmation modal closes correctly after deletion
• A success toast is shown on successful deletion; an error toast is shown on failure.
• The deleted message is also removed from the global message store.

Fixes #1208

Note: The PR will be ready for live testing at https://rocketchat.github.io/EmbeddedChat/pulls/pr-<pr_number> after approval. Contributors are requested to replace <pr_number> with the actual PR number.

[CLAassistant]

All committers have signed the CLA.

[DammyCodes-all]

Replaced by #1212