IMAT: motion upgrade

[rerpha]

Realised I hadn't put this in a ticket.

IMAT's motion is being migrated from Galils to Beckhoff in entirety. Previously IMAT used a Beckhoff for just the large Z/Rot stage.

Things to do:

• sort out networking to the beckhoff
• re-set up ADS route
• change amsnetID
• remove galils from main configuration
• copy over axes.cmd
• copy over jaws.cmd
• copy over motionsetpoints.cmd
• copy over sampleChanger.cmd
  • fix this - dbd isn't loaded currently
• add toggle for axis velocity forwarding (we previously removed this due to a race condition within the beckhoff, but we should re-add it for future commissioning as it'll be fixed going forwards, but not retrospectively)
• add safety variables
• add the above to banner.xml
• add autosave functionality to tc motorextensions to persist homing routine names
• document safety system and any other items which need making clear for support calls etc.
• document FORWARD_VELO change: https://isiscomputinggroup.github.io/ibex_developers_manual/specific_iocs/motors/beckhoff/Beckhoff-commissioning.html#beckhoff-manual-commission-step
• remove any references to IMAT having galils in wiki pages and anywhere else relevant
• set .DLY to non-zero
• set .EGU as appropriate - can use stDescription.sUnits
  • make this and copy over to NDXIMAT when SC is done filling this part of stDescription out
• set soft limits up
• home vals? - use stHomingConfig.fHomePosition

[rerpha]

ISISComputingGroup/EPICS-motorExtensions#92 for tracking changes to settings and custom dbs for ADS vars.
ISISComputingGroup/EPICS-ioc#984 for velocity forwarding

[rerpha]

this ticket will close #6855 as a side effect.