Update tsickle and typescript

[DreierF]

Hi,

I had to fix various issues that appeared after updating the loader to the latest tsickle version.

• The output of tsickle is no longer goog.forwardDeclare but goog.requireType
• The validateOptions was (no longer) correct (uses the typings shipped with schema-utils now)
• emitWithTsickle has been deprecated in favor or emit
• tsconfig.json did not allow relative path's for e.g. outDir
• Arguments of the write callback have changed

Let me know if you have any questions :)