Add `ioc` CLI command to launch the RSM parameter IOC

[Osayi-ANL]

Issue

The RSM conversion-parameter IOC (GUI + headless CaIoc child process, accepts --prefix) has no entry in the DashPVA CLI — users must run python -m dashpva.consumers.ioc_rsm_parameter manually. Every other launchable component (sim, workbench, h5viewer, pyfai, bayesian, setup) is exposed as a DashPVA <command>, so the IOC is inconsistent and hard to discover.

• src/dashpva/consumers/ioc_rsm_parameter.py — the IOC module, only runnable via python -m …
• src/dashpva/cli.py — click group with all other commands, missing an ioc command

Fixes

• src/dashpva/cli.py — add a new @cli.command() named ioc that subprocesses python -m dashpva.consumers.ioc_rsm_parameter, with a --prefix click option forwarded to the module's --prefix argument, matching the existing workbench/h5viewer command pattern.

Acceptance Criteria

• Run DashPVA ioc — the RSM parameter IOC GUI launches (same as python -m dashpva.consumers.ioc_rsm_parameter).
• Run DashPVA ioc --prefix myprefix: — the IOC starts with that prefix.
• Run DashPVA --help — the ioc command is listed with a description.