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`

go.mod

@@ -16,6 +16,7 @@ require (
 	github.com/marusama/semaphore/v2 v2.5.0
 	github.com/mholt/archives v0.1.5
 	github.com/mitchellh/go-homedir v1.1.0
+	github.com/samber/lo v1.52.0
 	github.com/shirou/gopsutil/v4 v4.25.10
 	github.com/spf13/afero v1.15.0
 	github.com/spf13/cobra v1.10.1