remove $args arrays and refactor to use subrequests as needed

@dmfdmf @Guite @drak - please look this over carefully. this seems dangerous. I did a search for `{modfunc}` and `ModUtil::func()` and tried to refactor around those.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| Refs tickets  | #1788
| License       | MIT
| Doc PR        | -