Prevent parallel testplan executions on same runpath.

[petoa]

Bug / Requirement Description

Clearly and concisely describe the problem.

Solution description

Describe your code changes in detail for reviewers.

Checklist:

• Test
• Example (both test_plan.py and .rst)
• Documentation (API)
• News fragment present for release notes
• MS info leakage check
• For new driver: driver index page
• For new assertion: ui/pdf/std renderers, documentation
• For new cmdline arg: documentation

[zhenyu-ms]

can you add a functional testcase for this feature?

[Pyifan]

hi petoa, as we discussed offline, 1) let's add a new feature to avoid runpath conflict by adding and checking pid when regular testplan starts 2) the logic for remote testplan runpath shall probably in RemoteTestplan class rather than RemoteResouce because it is base class to many other classes 3) please add test and news frag