* Expose NewSessionContext function
When auth middleware or interceptor is being mocked by other service
then they can take help of `session.NewSessionContext` to store mocked
session data to request context.
* Initialize _log in auth at creating
* Allow excluding URLs in Auth middleware
* restructure rcloud-base as a single base controller
* updated master.rest
* moved sentry from internal to pkg as it is used by relay
* removing unused rpc and it's dependencies
* Fix usermgmt tests
* Don't redefine variables in rest file
Co-authored-by: Abin Simon <abin.simon@rafay.co>