feat(zb): list tests and test regex filter + misc
This change introduces the following changes to zb.
Test Filtering
===============
Allows users to selectively run tests by specifying
a standard regex that matches on the name of the test.
Test Listing
===============
Allows users to list out the available tests as well as
the matched tests when using the regex filter.
The documentation README has also been updated with
examples and the command help.
The documentation for skip cleanup has been updated.
Signed-off-by: Vishwas Rajashekar <dev@vrajashkr.com>