Refs #8922 Add support for nested history saving.
Refs #8922 Refactor history loading.
Refs #8922 Add support for loading nested histories.
Refs #8922 Fix bug with WorkspaceProperty.

Should only give the workspace a temp name if we have a pointer to a workspace.
Refs #8922 Add unit tests for nested WorkspaceHistory loading.
Refs #8922 Fix SaveNexus and SaveNexusProcessed to capture history.

SaveNexus and SaveNexusProcessed wouldn't append a record to the history.
This commit fixes that issue and leaves a record on the input workspace so the result is that we get a
complete history, but we lose the execution start time and duration.
Refs #8922 Fix unit tests.
Refs #8922 Remove commented out code in LoadNexusProcessed

It looks like history was loaded here at some point in the past. May as well remove this
while I'm here.
Merge remote-tracking branch 'origin/feature/8922_history_loading_performance'