Add tests for switch statements located in action bodies

[kfcripps]

As mentioned in p4lang/p4-spec#1362, the frontend passes currently produce valid IR for switch statements located in actions, but no tests exist to validate that (as all of the backends run the EliminatteSwitch midend pass, which errors out on switch statements in actions).

It would be nice if we could add tests to validate switch statements in actions somehow.

[kfcripps]

Maybe we don't need to have a test with a P4 program that has switch statements in actions and successfully compiles, because we have an error test for the p4test backend, for which we're still able to observe the output of the frontend passes, before the error occurs: https://github.com/p4lang/p4c/blob/main/testdata/p4_16_errors_outputs/issue3299-frontend.p4

@ChrisDodd @vlstill Do you think this is good enough?