tools/mgmt-tester: Add mgmt-tester coverage for controller capabilities

tools/mgmt-tester: Add mgmt-tester coverage for controller capabilities

This patch adds two test cases for the new Read Controller
Capabilities MGMT command. Since the command itself is simple, the test
cases are simple as well:

1. Ensures that providing invalid parameters to the request will result
in a failed MGMT response.

2. Ensures that if the controller is BT5 compliant, the Read Controller
Capabilities command will return a valid TX power range as expected,
otherwise fail.

Reviewed-by: Manish Mandlik <mmandlik@chromium.org>
Signed-off-by: Anuj Jain <anuj01.jain@samsung.com>
Signed-off-by: Ayush Garg <ayush.garg@samsung.com>