feat(web, server): Ability to use config file instead of admin UI (#3836)

* implement method to read config file

* getConfig returns config file if present

* return isConfigFile for http requests

* disable elements if config file is used, show message if config file is set, copy existing config to clipboard

* fix allowing partial configuration files

* add new env variable to docs

* fix tests

* minor refactoring, address review

* adapt config type in frontend

* remove unnecessary imports

* move config file reading to system-config repo

* add documentation

* fix code formatting in system settings page

* add validator for config file

* fix formatting in docs

* update generated files

* throw error when trying to update config. e.g. via cli or api

* switch to feature flags for isConfigFile

* refactoring

* refactor: config file

* chore: open api

* feat: always show copy/export buttons

* fix: default flags

* refactor: copy to clipboard

---------

Co-authored-by: Jason Rasmussen <jrasm91@gmail.com>

mobile/openapi/doc/ServerFeaturesDto.md

@@ -9,6 +9,7 @@ import 'package:openapi/api.dart';
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
 **clipEncode** | **bool** |  | 
+**configFile** | **bool** |  | 
 **facialRecognition** | **bool** |  | 
 **oauth** | **bool** |  | 
 **oauthAutoLaunch** | **bool** |  |