Refactor plugin lifecycle code

[mmorhun]

We must revise code which is responsible for plugins start and stop and also parts which is responsible for rpc connection.
Another thing to be done is to separate hosted stuff and make hosted folder contain only hosted instance related stuff (including moving hosted related bindings there).

[evidolob]

Tasks:

• Extract 'Hosted' (plugin development) code in separate extension (plugin-dev?)
• Remove Hosted prefix in file name and type names where it's not needed or use proper name instead. Use suggestion from Extract 'Hosted mode' in separate extension #5261 (comment)
• Split plugin-ext in extension(Theia UI part) and plugin runtime library(code which running in plugin node or webworker)

---

• Move api folder in common folder

[benoitf]

hello, is source code will only be in folders like src/browser, src/common and src/node, etc after that ?

[evidolob]

Yes

[tsmaeder]

I don't really understand what "hosted" stands for. Also, I would separate the stuff that runs a second instance for self-hosting into a separate module (that's what I first though "hosted" means, but that is not true).

[akosyakov]

It would be good to discuss decomposition on Theia dev conf if possible to cover different scenarios.

[tsmaeder]

A couple more things that I think we should do:

1. Separate plugin-ext and plugin-ext-theia
   The mechanism for running API should be separated form the code that provides the "theia" namespace.
2. Make "vscode" and "theia" contributed API's
   We have extensions points "(Main|Ext)PluginApiProvider" for contributing API and should use them. Let's eat our own dogfood!
3. Make HostedPluginProcess just another ServerPluginRunner. I see no reason why it's treated specially.
4. Provide a library for making backend init functions. For example, the code overriding the module loading is alway the same and copied for each API contribution

@akosyakov @benoitf @evidolob discuss next week in Stockholm? Also, we need a plan on how to introduce the refactorings to the community, since this may be breaking.