Add test-features recipe to justfile

Created a `.sh` script using the `cargo-hack` tool in order to easily test all feature combinations. This is done in `--release` mode to reduce the size of the compiled artifacts.

The script is located in a new `contrib` directory (same approach followed by `rust-bitcoin` crates). This will be useful for CI as well.

contrib/test_features.sh

@@ -0,0 +1,46 @@
+#!/bin/sh
+
+# Exit immediately if any command fails
+set -e
+
+# Install or update cargo-hack (will skip if up-to-date)
+cargo install cargo-hack --locked
+
+crates="\
+    floresta-chain \
+    floresta-cli \
+    floresta-common \
+    floresta-compact-filters \
+    floresta-electrum \
+    floresta-watch-only \
+    floresta-wire \
+    floresta \
+    florestad"
+
+for crate in $crates; do
+    # Determine the path to the crate
+    if [ "$crate" = "florestad" ]; then
+        path="$crate"
+    else
+        path="crates/$crate"
+    fi
+
+    # The default feature, if not used to conditionally compile code, can be skipped as the combinations already
+    # include that case (see https://github.com/taiki-e/cargo-hack/issues/155#issuecomment-2474330839)
+    if [ "$crate" = "floresta-compact-filters" ] || [ "$crate" = "floresta-electrum" ]; then
+        # These two crates don't have a default feature
+        skip_default=""
+    else
+        skip_default="--skip default"
+    fi
+
+    # Navigate to the crate's directory
+    cd "$path" || exit 1
+    echo "Testing all feature combinations for $crate..."
+    export RUSTFLAGS="-Awarnings"
+
+    # Test all feature combinations
+    # shellcheck disable=SC2086
+    cargo hack test --release --feature-powerset $skip_default --quiet
+    cd - > /dev/null || exit 1
+done

justfile

@@ -56,3 +56,7 @@ fmt:
 # Checks the formatting
 format:
     cargo +nightly fmt --all --check
+
+# Test all feature combinations for each crate using cargo hack
+test-features:
+    ./contrib/test_features.sh