Typescript changes

[herschel666]

• strongly recommend to extend hops-typescript's tsconfig.json
• check, that the compilerOptions target- and moduleResolution-properties aren't overwritten by the user
• speed up incremental builds by setting transpileOnly and compilerOptions.isolatedModules to true for the dev-server

I'm overall not happy with how the checks are done in the diagnosis()-hook & don't lead to an error. Does anyone have a good idea to improve that?

Also the transpileOnly-feature doesn't lead to compilerOptions.isolatedModules being set to true anymore since this PR, that apparently fixed this issue. Maybe we don't want to enable it either, but I'm not able to decide this now. 😑

[KnisterPeter]

To be honest I'm not sure on how isolatedModules behaves in ts-loader. I've used it without webpack only.
But I'm really sure that for example parcel is integrating with typescript that way. But it may have some special side effects with webpack.

[KnisterPeter]

I would say, lets try it out. If it does work as we hope/expect it to work, then we are a lot faster than without isolated modules.