* [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
* added regulation validator
* made regulations find_time and ban_time values duration notation strings
* added DefaultRegulationConfiguration for the validator
* made session expiration and inactivity values duration notation strings
* TOTP period does not need to be converted because adjustment should be discouraged
* moved TOTP defaults to DefaultTOTPConfiguration and removed the consts
* arranged the root config validator in configuration file order
* adjusted tests for the changes
* moved duration notation docs to root of configuration
* added references to duration notation where applicable
* project wide gofmt and goimports:
* run gofmt
* run goimports -local github.com/authelia/authelia -w on all files
* Make jwt_secret error uniform and add tests
* now at 100% coverage for internal/configuration/validator/configuration.go
James Elliott
Clément Michaud