check-sr-results: add report-txt property
Use it to extract `Total number of network controllers' for now.
Update the config file and the documentation.
Add a unit test.
Signed-off-by: 
Vincent Stehlé <vincent.stehle@arm.com>
Use it to extract `Total number of network controllers' for now.
Update the config file and the documentation.
Add a unit test.
Signed-off-by: Vincent Stehlé <vincent.stehle@arm.com>