Improve support for configuration CRDs

[izgeri]

The configuration CRDs are not currently documented as of cyberark/secretless-docs#186. We'd like to make some improvements to their usability and implementation so that they can be made generally available, and this includes:

• [ ] adding better tests
• [ ] adding support for config reloading:
  • refactor existing PoC config reloading functionality / replace with viper as appropriate
  • add logic around restarting proxy services
• [x] updating to use v2 config instead of v1 config

[izgeri]

v2 config issue is logged in #715