Chore: Move fusion client code

[iLLiCiTiT]

Changelog Description

Moved fusion client code next to server codebase.

Testing notes:

1. Create package of fusion and core.
2. Upload both to server.
3. Make sure AYON launcher is using client code from this PR (e.g using dev paths).
4. Fusion integration should work as before.

[ynbot]

Task linked: AY-4913 Move Fusion client code

[BigRoy]

@iLLiCiTiT do we still need the settings_category for most of these?

[BigRoy]

do we still need the settings_category for most of these?

Nevermind this - it seems there are no publish plug-in settings for Fusion currently and the Creator settings appear to work.

[BigRoy]

Seems to work great!

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Side note:
It's weird that there apparently are no publisher plug-in settings for AYON Fusion even though OpenPype did seem to have them?

So separately from this PR we might want to expose that again.

[iLLiCiTiT]

Side note:
It's weird that there apparently are no publisher plug-in settings for AYON Fusion even though OpenPype did seem to have them?

So separately from this PR we might want to expose that again.

Weird indeed, agree, different PR.