Make it easier to pass arguments to test executable

So option arguments like `--test-threads=1` that must come after
`--` can be passed through `just` to `cross`, while still being
able to customize options like `--features` that go before it.

Author: EliahKagan

justfile

@@ -231,17 +231,17 @@ cross-image target:
         -f etc/docker/Dockerfile.test-cross etc/docker/test-cross-context
 
 # Test another platform with `cross`
-cross-test target *cargo-test-args: (cross-image target)
+cross-test target options test-options: (cross-image target)
     CROSS_CONFIG=etc/docker/test-cross.toml NO_PRELOAD_CXX=1 \
         cross test --workspace --no-fail-fast --target {{ target }} \
-        {{ cargo-test-args }} -- --skip realpath::fuzzed_timeout
+        {{ options }} -- --skip realpath::fuzzed_timeout {{ test-options }}
 
 # Test s390x with `cross`
-cross-test-s390x: (cross-test 's390x-unknown-linux-gnu')
+cross-test-s390x: (cross-test 's390x-unknown-linux-gnu' '' '')
 
 # Test Android with `cross` (max-pure)
-cross-test-android: (cross-test 'armv7-linux-androideabi' \
-                     '--no-default-features' '--features' 'max-pure')
+cross-test-android: (cross-test 'armv7-linux-androideabi'
+                     '--no-default-features --features max-pure' '')
 
 # Run `cargo diet` on all crates to see that they are still in bounds
 check-size: