LSP: Fix type bind, mark as experimental, deprecate direct LSP access

[HolonProduction]

Fixes (not anymore) #52162
Fixes (not anymore) #86132

The LSP types were not added at the right time, so they were not picked up at some places e.g. by the doctools (internal documentation recognized them though).

This PR binds them at the correct time to get picked up by the doc tools. The classes are now marked as experimental, the amount of internals that is exposed makes implementation of new LSP features while keeping behavior of all those methods infeasible.

In addition this PR marks some methods as deprecated:

• Methods that have the primary purpose of interacting with connected clients: The LSP is not meant to be extendable and usage of those methods isn't possible in a meaningful way, since there is no way to actually obtain information about the connected clients
• Methods that directly implement an LSP endpoint: Those had to be exposed due to how JSONRPC functioned before JSONRPC: Require manual method registration #104890 . They are not save to access as public API though for two reasons:
  1. They expect to be communicating with an compliant LSP client, so users would have to ensure to follow the LSP lifecycle when using those, it's unlikely that they will.
  2. Some of those methods rely on context from the networking code (which peer is processed at the moment). When accessing those methods not through the networking code this context isn't set correctly, which could lead to incorrect behavior.

[HolonProduction]

Updated to also fix the timing of registering the singleton, thus fixing two old issues about it.

[Mickeon]

If this is approved by others, the methods that are not deprecated should absolutely provide a meaningful description.

[HolonProduction]

Seems like singletons must directly inherit Object. Not sure how to precede here 🤷

[Calinou]

Suggested change

	Returns whether the language server is providing the smart resolve feature. The feature can be configured through the editor settings.
	Returns [code]true[/code] if the language server is providing the smart resolve feature, [code]false[/code] otherwise. The feature can be configured using [member EditorSettings.network/language_server/enable_smart_resolve].

[HolonProduction]

The editor settings does not show up in the docs, so I'd rather not add a link which might be broken.

[HolonProduction]

I removed the singleton binding from this PR:

What does this PR do now:

• Bind types at correct time for doc tool
• Add documentation for LSP classes
• Marks LSP classes as experimental
• Deprecates a lot of methods for the reasons mentioned above

The singleton binding is still broken. This should be tackled separately.

[akien-mga]

Looks good to me.

[Repiteo]

Thanks!