refs #10131. Worker class put in place.
refs #10131. Implement checkGroups

I've actually called it what it is instead. findMultiPeriodGroups. I also really dislike the confusing side effects caused by the existing Algorithm::checkGroups, so I've decided not to go with that design, and instead have findMultiPeriodGroups as a const method.
refs #10131. Implemented processGroups.

Tests put into place to verify process groups.
refs #10131. MultiPeriodWorkspaceAlgorithm refactored.

Now uses worker instance.
refs #10131. Cannot use typename outside of template.
refs #10131. Fix doxygen warnings.
Revert "refs #10131. Fix doxygen warnings."

This reverts commit adf33460ed0d4900db5f8d6806bbefbbe0e71793.
Revert "refs #10131. Cannot use typename outside of template."

This reverts commit 9e70c2bb468e968e1fb5ccb13d1b1c2bc193b464.
Revert "refs #10131. MultiPeriodWorkspaceAlgorithm refactored."

This reverts commit 62747a94726ff21cfe75e2bf4e9a4a0e732fae24.
Revert "Revert "refs #10131. Fix doxygen warnings.""

This reverts commit 357ea038305af950a6e97ed72ec1e333f506d790.
Revert "Revert "refs #10131. MultiPeriodWorkspaceAlgorithm refactored.""

This reverts commit d4440e725eff57aa87df5b4acb77264bf24f2940.
Revert "Revert "refs #10131. Cannot use typename outside of template.""

This reverts commit 11ba43d8a0a62b42d911a53420b77f7d63e44b01.
refs #10131. Fix broken test and functionality.
refs #10131. Fix windows build.
Merge remote-tracking branch 'origin/feature/10131_process_groups'