This allows to specify folders to be used as search folders
while scanning for tests.
Current approach allows simple folder names or folder structures
without wildcards.

Examples:
Value                What will be (recursively) scanned
tests                if the current project has any (not necessarily
                     a direct) subfolder 'tests' this folder will be
                     scanned
tests/auto           if the current project has any (not necessarily
                     a direct) subfolder 'tests' and this folder has
                     a direct subfolder 'auto' the 'auto' folder will
                     be scanned
If there are more folders which apply to the rules then all of them
will be scanned.
This filtering will not keep the parser inside these folders as it
might be necessary to step into different folders because of
dependencies if the found tests, but the search for entry points to
tests will be limited to these folders.

Task-number: QTCREATORBUG-16705
Change-Id: Ib93465540cd20656d033e16205807aba6830d738
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: David Schulz <david.schulz@qt.io>