Beckhoff: Use direction from PLC

[DominicOram]

As a developer I would like the Beckhoff PLC to tell me which direction it is moving in, rather than calculating it myself inside the motor record.

Acceptance Criteria

• [ ] The TWINCAT motor record gets its direction directly from the PLC rather than calculating it

Extra Information

• The direction is now exposed in the PLC side https://bitbucket.org/europeanspallationsource/tc_mca_std_lib/pull-requests/44

[rerpha]

tcioc: https://github.com/ISISComputingGroup/EPICS-tcIoc/pull/9 RN: https://github.com/ISISComputingGroup/IBEX/pull/6802

[rerpha]

Tests all passing, there are already tests for direction. Hooray for TDD