add `IsException`, `IsError`, and `IsThrowable` selectors #515

Job	Run time
Tests (7.4, highest)	17s
Tests (8.0, highest)	23s
Coding Standards (8.3, highest)	12s
Tests (8.1, highest)	14s
Static Code and Architecture analysis (7.4, highest)	51s
Tests (8.2, highest)	13s
Static Code and Architecture analysis (8.0, highest)	23s
Tests (8.3, highest)	17s
Static Code and Architecture analysis (8.1, highest)	25s
Static Code and Architecture analysis (8.2, highest)	20s
Static Code and Architecture analysis (8.3, highest)	20s
	3m 55s

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