sencha: set path to testbench firmware
Depending on the default path in cheriot.resc was too fragile.
Bypass-Presubmit-Reason: no CI tests for sencha
Change-Id: I8f45ea45205e1d426c711a1af2b013481ead2d5a
This is the project containing all the top-level build targets of all the projects within the GoB to set up the environment and build the e2e artifacts.