Implement a simple solution re #6335

Make InstrumentDefinitionParser use getComponentByName if a '/' is found in the component's name.
Component is assumed unique if there is a '/' in its name.

Signed-off-by: Karl Palmen <karl.palmen@stfc.ac.uk>
Modify Test file to test this feature re #6335

Signed-off-by: Karl Palmen <karl.palmen@stfc.ac.uk>