Build: Fetch t_cose lib into the shared folder

Fetch the t_cose library into the shared folder so
later it can be copied to the individual job workspaces.

TF-M switched from using its internal t_cose fork to use
the upstream t_cose repository thus TF-M tries to fetch it
during the CMake configuration step.

Signed-off-by: David Vincze <david.vincze@arm.com>
Change-Id: I2fe9840028ed981bb4a1de9be1ef908c67dfd960
5 files changed