Generate declaration file for process builder

[m-mohr]

Add a way to generate TS declaration files from the process descriptions obtained from the back-ends for the methods added to the Builder. This would allow much better IDE integration. By default it could be generated from the original processes, but we could likely add CLI commands that generate them for the individual back-ends.

Example: npm run process-tsd -- -- {serverUrl} - if no serverUrl is given it generates either for all back-ends from the Hub or the default for the original processes (probably the latter?).