Add test for Result<bool>, fix sfinae

Add an explicit test for Result<bool>, showing usage with the explicit factories. It also fixes a small inconsistency in the detection of ambiguity between the two types of Result.

changed milestone to %0.09.00

added Improvement label

For job clang_tidy on commit: 66a51220

Static analysis results: Accepted

ok	pattern	count	limit
	readability-inconsistent-declaration-parameter-name	0	0
	readability-named-parameter	0	0
	readability-container-size-empty	0	0
	modernize-use-using	0	0
	modernize-use-override	0	0
	readability-implicit-bool-cast	0	0
	modernize-use-default-member-init	0	0
	performance-unnecessary-value-param	0	0
	modernize-use-equals-default	0	0
	modernize-use-nullptr	0	0

Analysis results at: https://gitlab.cern.ch/api/v4/projects/3031/jobs/3944865/artifacts

approved this merge request

approved this merge request

merged

mentioned in commit 7e36a11a

mentioned in merge request atlas/atlasexternals!481 (merged)