Macro instantiate_global_policy_checker_tests

macro_rules! instantiate_global_policy_checker_tests {
    ($fixture_impl:path) => { ... };
    ($fixture_impl:path, $test:ident, $($remaining:ident),+ $(,)?) => { ... };
    ($fixture_impl:path, $test:ident) => { ... };
}

These GlobalPolicyChecker tests are run under multiple contexts, e.g. both on Fuchsia under component_manager and on the build host under cm_fidl_analyzer. This macro helps ensure that all tests are run in each context.