ci: Add workflow tests for direct-xip and ram-load

Although there are no tests for these cases, the configurations now are
built.  Enabling them in CI will ensure they continue to build.

Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/.github/workflows/sim.yaml b/.github/workflows/sim.yaml
index 374788d..d1d65b7 100644
--- a/.github/workflows/sim.yaml
+++ b/.github/workflows/sim.yaml
@@ -33,6 +33,8 @@
         - "sig-ecdsa-mbedtls enc-ec256-mbedtls validate-primary-slot"
         - "sig-ecdsa-mbedtls enc-aes256-ec256 validate-primary-slot"
         - "sig-rsa validate-primary-slot overwrite-only downgrade-prevention"
+        - "sig-rsa validate-primary-slot ram-load"
+        - "sig-rsa validate-primary-slot direct-xip"
     runs-on: ubuntu-latest
     env:
       MULTI_FEATURES: ${{ matrix.features }}