[TS] Actually import typescript extension in typescript generator

[hhvrc]

Is there any reason these are importing .js extensions in the typescript generator?

They should be importing .ts so i changed it

[bjornharrtell]

I'm not aware of importing modules with .ts extensions being a thing at all. Either it's with .js extension as that is the compiled target explicit module name, or it can sometimes be acceptable with extensionless module name depending on runtime environment.

Unless some very convincing motivation is given here I would suggest to close this.