* fix: redis sentinel secret missing
* refactor: use consts for authentication_backend.file.password errs
* fix: unit test for new default port
* test: cover additional misses
* test: fix windows/linux specific test error
* test: more windows specific tests
* test: remove superfluous url.IsAbs
* test: validator 100% coverage
* [FEATURE] File Secret Loading
* add a validator for secrets
* run the secrets validator before the main config validator
* only allow a secret to be defined in one of: config, env, file env
* remove LF if found in file
* update configuration before main config validation
* fix unit tests
* implement secret testing
* refactor the secrets validator
* make check os agnostic
* update docs
* add warning when user attempts to use ENV instead of ENV file
* discourage ENV in docs
* update config template
* oxford comma
* apply suggestions from code review
* rename Validate to ValidateConfiguration
* add k8s example
* add deprecation notice in docs and warning
* style changes
James Elliott
Amir Zarrinkafsh