Allow SYNC TEAM team-value to be a child team

[nathanweeks]

Summary of changes

Fix #655 by allowing the SYNC TEAM team-value argument to be a child team.

Added a unit test.

Rationale for changes

Fortran 2018 standard compliance (and I need it for an application).

Additional info and certifications

This pull request (PR) is a:

• Bug fix
• Feature addition
• Other, Please describe:

I certify that

• I certify that:
  • I have reviewed and followed the [contributing guidelines]
  • I will wait at least 24 hours before self-approving the PR to give another
    OpenCoarrays developer a chance to review my proposed code
  • I have not introduced errant white space (no trailing white space or white space errors may
    be introduced)
  • I have added an explanation of what these changes do and why they should be included
  • I have checked to ensure there aren't other open [Pull Requests] for the same change
  • I have you written new tests for these changes
  • I have successfully tested these changes locally
  • I have commented any non-trivial, non-obvious code changes
  • The commits are logically atomic, self consistent and coherent
  • The [commit messages] follow [best practices]
  • Test coverage is maintained or increased after this is merged

[codecov]

Codecov Report

Merging #656 into master will increase coverage by 0.46%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #656      +/-   ##
==========================================
+ Coverage    54.1%   54.56%   +0.46%     
==========================================
  Files           3        3              
  Lines        2924     2925       +1     
==========================================
+ Hits         1582     1596      +14     
+ Misses       1342     1329      -13

[zbeekman]

Thanks so much @nathanweeks!