Deprecating dexctl’s --db-url flag. Achieve feature parity between existing commands and the bootstrapping API, then have all dexctl actions go through that.
* Overarching issue of deprecating --db-url flag (#298)
* Add client registration to bootstrapping API (#326)
* Set connector configs through bootstrapping API (#360)
## Further server side cleanups
Establish idioms for handling HTTP requests, create a storage interface for backends, and continue to improve --no-db mode.
* Improve server code and storage interfaces (#278)
* Fix client secrets encoding in --no-db mode (#337)
* Easier specification of passwords in --no-db mode (#340)