…lter tool

Through this change we will run the tests suggested by the spread-filter
tool following the rules located in tests/lib/spread/rules which defined
for each system.

For nested tests, this ruleset will make sure that:
. Always that the nested.sh lib or the assertions dir are updated, all
the nested test are executed
 . When an specific nested test is updated, then this is executed
. If the "Run Nested" label is added to the PR, all the nested tests
will be executed as well.
 . In master branch, all nested test are executed
 . In other scenarios, nested tests are not executed.

Also, in master branch, all the tests are executed (the tests defined in
the matrix for each system).

This produced issues for example running all the nested tests when it is
not needed.