Text validator catches answers of the wrong case
Start fix for the how the set type of answers deal with messages
Display check answer message when the answer is of type set-sol
Incorporate suggestions
Merge pull request #43253 from petercollingridge/case-hints

Case hints

fix #41331; fix #42800; fix #42496; fix #42169; fix #34703; fix #32321; fix #26721; fix #34703;
Will have to make a separate fix for regex style solutions

Test Plan: Test a few examples of http://localhost:8000/exercises/exploring_angle_pairs_1.html
And:
http://localhost:8000/exercises/points_lines_and_planes.html?debug&problem=name-plane

Auditors: beneater, spicyj or cbhl