feat(turborepo): new ui + watch mode (#7962)
### Description
Integrates new UI with watch mode. Pulls out the UI handle and sender
outside the `Visitor` and `Run` struct, so it can be owned by the
`WatchClient`. Also adds an `Event` for updating the task names, so on
rediscovery we can keep using the same UI thread but just update the
task names.
### Testing Instructions
Give it a shot!
Closes TURBO-2801
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Co-authored-by: Chris Olszewski <chris.olszewski@vercel.com>
