[TASK] Four usability changes

1. Feature to set per-flux-form value of `useTypoScript` as part of form's `options` array. Setting this overrides the TS-defined value.
2. Entry-level defaults moved to `{settings}` scope in order to be easier accessible. Isolated in own sub-scope to avoid conflict.
3. Usages of `v:var.set` to set temporary variables, switched to inline use of `f:if` to condition special CSS class names.
4. Element `ProgressBar` set to locally disable the `useTypoScript` parameter.