Fix failing "Go to Definition" for some types

[peterbozso]

Fixes #924

As explained in #924, "Go to Definition" doesn't work for some types.

There are three different problems described in that issue.

First problem

"Go to Definition" doesn't work for types with constructors and/or operators (like String or Vector2i).

This PR is a full fix only for this. Now those types get their documentation properly generated.

I also added a safeguard for the future: in case the LSP surfaces other properties not handled by this extension, the extension will still generate the documentation it can while printing the problem of unhandled property types to the debug log.

Second problem

"Go to Definition" doesn't work for types with properties containing multiple forward slashes (/) in their names, like ProjectSettings.

This is partially fixed in this PR too: the documentation for ProjectSettings opens, but it's missing a bunch of properties.

This happens because of this:

godot-vscode-plugin/src/providers/documentation_builder.ts

Line 144 in e99adb0

const parts = /\.([A-z_0-9]+)\:\s(.*)$/.exec(s.detail);

ProjectSettings has hundreds of properties with / in their names (e.g., application/boot_splash/bg_color, display/window/size/viewport_width). These come from the engine's ProjectSettings.xml doc file, where each engine setting is documented as a class member. The LSP produces detail strings like:

var ProjectSettings.application/boot_splash/bg_color: Color

The regex character class [A-z_0-9] does not match / (ASCII 47 is outside the A=65 to z=122 range). So parts is null, the function returns undefined, and the caller crashes on elements.index (line 242) with a similar TypeError.

After this PR is merged, I'll open a separate issue to track this.

Third problem

In the second half of this comment, I brought up a problem with navigation to TileMapLayer's methods. This bug is completely unrelated to the other two. I'll open a separate issue in the engine's repo to track that too.

[DaelonSuzuka]

This looks great, thanks! (And thanks in advance for keeping track of the other issues.)