Refs #10223 Add group rows button

* Add group rows button to Refl UI
* Add unit test for group rows button
Refs #10223 Tidy up BlankReflMainViewPresenterTest

* Remove superfluous asserts
* Factor out magic numbers
* Reorder asserts for readability
* Correct some whitespace
Merge branch 'feature/10223_new_refl_ui_improvements' into develop