Generate GDJS types

[arthuro555]

Instead of bundling both the built and non-built runtime for autocompletion, we could generate type definitions with tsc and bundle those with GDevelop for autocompletions. This should help make GDevelop more lightweight (and I must admit that my primary motivation is that this would also be pretty useful for type checking external tools that use the gdjs api, like my modding tool gdmod and other tool ideas I have)

[4ian]

Yes! That's even a comment in the codebase ;)

GDevelop/newIDE/app/src/CodeEditor/LocalCodeEditorAutocompletions.js

Lines 40 to 47 in f3a49ad

	// Autocompletions are generated by reading the sources of the game engine
	// (much like how autocompletions work in Visual Studio Code) - *not* the built files.
	// The built files are stripped of their types and documentation, so it would
	// not work.
	//
	// We could also use the TypeScript compiler to emit .d.ts files when building GDJS,
	// but this would make TypeScript slower (at least 2x slower) and we would still need
	// to copy and read an equivalent number of files.

By doing this, we can remove the copy of the sources (which is now done anyway only when starting or bundling the IDE). But we have to change the TS config to export these type definitions (takes a bit more time for tsc) and output them in a place where read by the IDE (and ensure this is done before bundling).

[arthuro555]

If it increases tsc "build" time that much, maybe we can have two tsconfigs and two npm scripts running tsc with those two configs (check-types and generate-dts), with one exclusively for type checking and the other for also emitting declarations.