feat(mdtest run/auto): support specifying test script paths from command
line arguments.

mdtest now supports reading test suites paths from command line
arguments.  It will treat anything besides the supported command line
flag/option as the path pattern for the test scripts.  Users can specify
multiple glob patterns for their test scripts.

Now mdtest is able to find test script paths from both test spec and
command line arguments.  Users can specify glob patterns in both test spec
or command line.  The convention is that relatively stable test script
paths should be specified in the test spec and other frequently modified
test script should be specified from the command line.

The behavior of the current implementation is that test paths in the
test spec will be executed before test paths specified in the command line.
Duplicated test paths will be ignored and only the first test path
position is kept.  If a user specifies multiple glob patterns, the test
paths corresponding to each glob pattern will be executed in the order
of their appearance.  However, the order of executions for test paths
within the same glob pattern is not guaranteed.

Change-Id: Ibefc789e4c17cbf12ecd054171e95c1099d6f0de
6 files changed