add `IsException`, `IsError`, and `IsThrowable` selectors #518

Job	Run time
Coding Standards (8.3, highest)	20s
Static Code and Architecture analysis (7.4, highest)	26s
Static Code and Architecture analysis (8.0, highest)	25s
Static Code and Architecture analysis (8.1, highest)	23s
Static Code and Architecture analysis (8.2, highest)	26s
Static Code and Architecture analysis (8.3, highest)	26s
Tests (7.4, highest)	34s
Tests (8.0, highest)	18s
Tests (8.1, highest)	20s
Tests (8.2, highest)	16s
Tests (8.3, highest)	17s
	4m 11s

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