SF-2956 Fix import question dialog offline error message color

[Nateowami]

Fixes the color of the offline error messages (previously they were black).

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This change is 

[marksvc]

This is reviewable in Devin Review.

[codecov]

❌ 2 Tests Failed:

Tests completed	Failed	Passed	Skipped
4871	2	4869	3

View the top 2 failed test(s) by shortest run time

.ImportQuestionsDialogComponent Import from Paratext::ImportQuestionsDialogComponent Import from Paratext disables import button when user is offline

Stack Traces | 0.021s run time

Error: Expected undefined to equal 'Importing from Paratext is not available offline.'.
    at <Jasmine>
    at UserContext.<anonymous> (.../checking/import-questions-dialog/import-questions-dialog.component.spec.ts:560:36)
    at UserContext.fakeAsyncFn (node_modules/zone.js/fesm2015/zone-testing.js:1715:26)
    at _ZoneDelegate.invoke (node_modules/zone.js/fesm2015/zone.js:398:28)

.ImportQuestionsDialogComponent::ImportQuestionsDialogComponent does not try to load transcelerator questions when the user is online

Stack Traces | 0.036s run time

Error: Expected undefined to equal 'Importing from Transcelerator is not available offline.'.
    at <Jasmine>
    at UserContext.<anonymous> (.../checking/import-questions-dialog/import-questions-dialog.component.spec.ts:518:34)
    at UserContext.fakeAsyncFn (node_modules/zone.js/fesm2015/zone-testing.js:1715:26)
    at _ZoneDelegate.invoke (node_modules/zone.js/fesm2015/zone.js:398:28)

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[marksvc]

Thank you. BTW, I notice that there are a number of other mat-error element usages in this class. If the problem is that mat-error was being used outside of mat-form-field, then there are a few other places where the text will similarly not be styled as intended.

@marksvc reviewed 1 file and all commit messages, and made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on Nateowami).