Implement @ets inline

[0x706b]

discord link

So an idea, we could in theory have a generic @ets inline that works like:

1) if specified in a function in a .ts file it ensures the function body doesn't access any external symbol except the arguments
2) emits in the .d.ts an added text to the jsdoc like @ets inline self.map(f)
3) when a call expression uses it the compiler inline the implementation

This requires a few tricks though:
1) to process the .d.ts we need to extend the Parser to produce a valid ast and check the ast like any normal TS
2) the .d.ts and the plain .ts should end up with the same ast structure
3) the transformer needs to parse and replace the identifiers in the ast respective to the function arguments, if the body isn't a simple expression but a body like {return ...} the function should be inlined fully and called