CLC-4321 - Investigate possible issues with pending eGrades Export tool

https://jira.ets.berkeley.edu/jira/browse/CLC-4321

Provides validation and appropriate error display when state of course site not appropriate for eGrade Export. Ensures that export uses letter grade provided by Canvas via Grading standard/schemes, and only includes student grades from selected section.
No. Each step of the initialization is open to error, and I'm wanting only the first error detected to be displayed, so as to not overload the user. Also, other errors may be due to previous ones.

For instance, if there are no terms associated with the course site sections, there will also not be any official sections loaded. I'm only wanting one of those errors to be triggered and displayed.