ENGIN-X / IMAT: Instron (Stress Rig): Automate loading of channel type specific records

As a programmer I would like to automate the loading of channel type specific records of the Instron Stress Rig.

**Acceptance Criteria**
Rather than having to load extra dbs in st.cmd manually, the extra records are loaded based on the channel type returned by the rig.

**General Notes**
This ticket is of low priority in relation to the Instron. This ticket should be done after Tickets
- [ ] #2111,
- [ ] #2112
- [ ] #2113

The rig in use consists of the channels, Position (POS) on Channel 1, Stress (STRESS) on Channel 2, ans Strain (STRAIN) on Channel 3.

There is a lot of information to support the stress rig work in a folder called Instron Stress Rig in the ICP discussions area of our local SharePoint. Items below are highlighted as being relevant to this ticket directly, some of the other information may be required from the other documents.

The PV names may not have included a $(P) or the correct number and position of `:`, and may not be the final names used, as clarity here was chosen over following the guidelines. Please use appropriate names, and if different from those in the documents - update the documents as you go