Expose build errors and warnings via GraphQL

[williamjallen]

This PR continues our ongoing effort to expose most of the database schema via GraphQL.

[williamjallen]

Paused until #2183 is merged.

[josephsnyder]

The GraphQL changes in the Explorer look good. After doing a little exploring with the CTest data, I was able to find a place where I thought things didn't align but the GraphQL return matches the data found in the build table

[williamjallen]

After discussion, it looks like there are some issues that need to be resolved before this can be merged. The buildWarningsCount being wrong isn't terribly surprising given that this information was not generated by our regular submission process, but the fact that no warnings were selected is concerning.

Needs further work. Current functionality works as intended, but intended purpose was not the best long-term design decision.

[williamjallen]

@josephsnyder I think this is ready for a re-review.

The issue you observed is the result of my confusion about the fact that CDash stores two different types of warnings or errors. Adding the other type of warnings/errors to the API will be a significant undertaking, so I think it should be done in another PR (or several). This PR specifically adds the "basic" errors and warnings stored in the builderror table. Functionally, it should be equivalent to the behavior during your last review.

To reduce confusion about the fact that "build errors" can actually be warnings, I have created the term "build alert" to refer to the collection of both errors and warnings, with "build errors" and "build warnings" being more specific types of build alerts. Furthermore, I have created the terms "basic" and "rich" alerts to refer to the contents of the builderror and buildfailure tables respectively. To get all of the errors or warnings for a given build, one must query both the basic and (yet-to-be-implemented) rich errors or warnings. I'm open to suggestions regarding better terminology for any of these.

It would be good for @zackgalbreath to review this as well, particularly the documentation and terminology changes.

[josephsnyder]

I can see the BasicBuildAlert doc type and it does nicely translate to a query where you can ask for a build for it's basicWarnings and BasicErrors with the context, line, and all the other expected fields. It LGTM but I'll hold off on adding it to the merge queue to give Zack a chance to chime in