fix: add missing click dependency

Click is used in parts of the CI scripts (see run_config/fvp-linux.tc
for instance), add it back as part of a new dependency group. Future
dependencies that are required only in CI should be added to the
``ci`` dependency group.

Change-Id: I5da7fea703495dd4006d86334626f126a850bb10
Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>