Fix coroutines when running from File > Remote Development

For whatever reason, cs.launch does not work and you have to pass the
modality state.  Without this state, they do not launch until after the
remote development window is closed.

Using that from a background process fails, however (something about
only being able to access from EDT), so instead of starting/stopping the
poll there, I just always keep it running in the background (and it just
does nothing when there is no client).

For the re-invoking of the token window, I removed the launch entirely.
Could probably use invokeLater() or something but this seems fine?

Fix multiple clients launching with running backend

Implement backend monitoring

This implements connecting at a lower level, giving us a place to
respawn the backend and reconnect when it goes down, replacing
fullDeployCycle since it does not do that for us.

Closes coder#392.

Clear recent connections client on error

This will at least give you the opportunity to fix it manually by going
through the new connection flow, until code is added to ask for a token.

Fix exception when no URL yet

toURL() will throw if the string is blank, which it will be on the very
first time Gateway is launched.

chore: bump gradle/wrapper-validation-action from 3.3.1 to 3.3.2 (cod…

…er#406)

Bumps [gradle/wrapper-validation-action](https://github.com/gradle/wrapper-validation-action) from 3.3.1 to 3.3.2.
- [Release notes](https://github.com/gradle/wrapper-validation-action/releases)
- [Commits](gradle/wrapper-validation-action@v3.3.1...v3.3.2)

---
updated-dependencies:
- dependency-name: gradle/wrapper-validation-action
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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2.10.0

Update to 2.9.4

Add test for proxy authorization