feat: consistent flags and environment variables (#5549)

- In the root command, all flags are now correctly available as environmental variables, except for `--config` flag. This was already supposed to be the case, but due to bugs in the implementation it didn't work properly.
- All configuration options (unless I missed something) that are available as flags should now properly update the configuration when using the `config init` and `config set` commands.
- Flag names are now consistently in the lowerCamelCase format. All flags that were in a different format have been updated in a backwards compatible way. For a transitionary period of at least 6 months, both will work:
  - `--dir-mode` --> `--dirMode`
  - `--hide-login-button` --> `--hideLoginButton`
  - `--create-user-dir` --> `--createUserDir`
  - `--minimum-password-length` --> `--minimumPasswordLength`
  - `--socket-perm` --> `--socketPerm`
  - `--disable-thumbnails` --> `--disableThumbnails`
  - `--disable-preview-resize` --> `--disablePreviewResize`
  - `--disable-exec` --> `--disableExec`
  - `--disable-type-detection-by-header` --> `--disableTypeDetectionByHeader`
  - `--img-processors` --> `--imageProcessors`
  - `--cache-dir` --> `--cacheDir`
  - `--token-expiration-time` --> `--tokenExpirationTime`
  - `--baseurl` --> `--baseURL`

cmd/config_import.go

@@ -37,7 +37,7 @@ The path must be for a json or yaml file.`,
 	RunE: python(func(_ *cobra.Command, args []string, d *pythonData) error {
 		var key []byte
 		var err error
-		if d.hadDB {
+		if d.databaseExisted {
 			settings, settingErr := d.store.Settings.Get()
 			if settingErr != nil {
 				return settingErr
@@ -104,7 +104,7 @@ The path must be for a json or yaml file.`,
 		}
 
 		return printSettings(file.Server, file.Settings, auther)
-	}, pythonConfig{allowNoDB: true}),
+	}, pythonConfig{allowsNoDatabase: true}),
 }
 
 func getAuther(sample auth.Auther, data interface{}) (interface{}, error) {