Description of the problem / feature request:

Provide a test_exec_properties option for *_test rules.

Feature requests: what underlying problem are you trying to solve with this feature?

The test execution platform properties should be differentiated from exec_properties. Currently setting an exec_properties of a *_test will apply to the actions used to build the target, as well as the test itself. In order to apply specific runtime configurations to the platform of the test, but not, say, the compiles of a cc_test, a different rule attribute is required.