Updated tests for constant expressions.

Test: `make android.hardware.tests.expression@1.0` compiles
      and generates enum class Color with autofilled values.
Test: `make hidl_test_java` succeeded.
Test: `make hidl_test` succeeded.

Bug: 31628863 Add test for autofilling enum values.
Bug: 31592132 allow constant expressions be array sizes.

Change-Id: I79f35365f1d37843922725ad5a405848f3e8ec08