Unit test - multiple test apps

[edanor]

Originally reported by: edanor (Bitbucket: edanor, GitHub: edanor)

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Compiling current test suite takes insane amounts of time. For development purposes only a minimal set of tests is required, usually regarding single SIMD type being specialized. Separate testing apps can be provided to compile only tests for required type. This would also allow faster parallel builds.

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• Bitbucket: https://bitbucket.org/edanor/umesimd/issue/40