Remove commands that only tell us that they only work from the sidebar

[mjambon]

Is there a way to invoke these commands from the sidebar without an error? If so, this should be explained to the user.

This PR removes the pattern search/replace commands since there doesn't seem to be a way to make them work.

test plan: run the extension, check that Ctrl+Shift+p doesn't list the commands to search and replace.

PR checklist:

• Purpose of the code is evident to future readers
• Tests included or PR comment includes a reproducible test plan
• Documentation is up-to-date
• A changelog entry was for any user-facing change
• Change has no security implications (otherwise, ping security team)

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