Previously, there are too many hacked stuffs such as `__FSIO_1',
`lstgrp_noio', `lstgrp_io' out there in `z_erofs_vle_submit_all'.
Revisit the whole process by properly introducing jobqueue to
represent each type of queued workgroups, furthermore hide all of
crazyness behind independent separated functions.
After this patch, 2 independent jobqueues exist if managed cache
is enabled, or 1 jobqueue if disabled.