rtk rewrite --unknown to identify tool calls not covered yet

[reneleonhardt]

Similar to rtk gain --history, would it be possible to list the commands for which rewrite support hasn't been implemented yet?

MiniMax Code used the full path instead of just xcodebuild, and prepending env variables like DEBUG=1 xcodebuild isn't covered either by the current regex.

Output would be the unsupported command and the output length to prioritize which missed opportunities to implement next.

Unknown command	Total output size
DEBUG=1 xcodebuild	20 MB