Reconsider the architecture for mini-insts/cut down instruments

As someone wanting to use instantiations of IBEX which are less than the full server I want to clear up what the requirements, and come up with a plan to resolve this.

## Acceptance Criteria
- [ ] The various types of cut down IBEX setup are documented
- [ ] The documented use cases are then presented to the group and an architecture decision made on how to proceed
- [ ] Tickets are created to start enacting that decision

## Notes
- The last two points may need to be spun out into separate tickets
- This is not being added to the discussion list as there needs to be a better understanding of the use cases before the work can be undertaken
- Examples of systems which could benefit from not having to run a full IBEX server potentially: HIFI Cryomag; Triton PCs; Instron PC; HLM system; any remaining SECI instruments; CHIPIR
- #7450 may be useful in considering this architectural decision