chore: add cargo hack check to bin/publish (#1950)

This adds a check to the `bin/publish` script that the crate being
published builds successfully with all possible feature combinations,
using `cargo hack --feature-powerset`.

This would have prevented #1944.

We test this on CI for most crates in the repo, but it's disabled for some
crates because the powerset is very large, making the check too slow
to run on CI. However, adding it to the publish script will ensure that it's
at least always run before publishing a crate.

bin/publish

@@ -31,6 +31,18 @@ verify() {
         exit 1
     fi
 
+    if ! cargo list | grep -q "hack"; then
+        status "Installing" "cargo-hack"
+        cargo install cargo-hack
+    fi
+
+    status "Checking" "if $CRATE builds across feature combinations"
+
+    if ! cargo hack check $VERBOSE --feature-powerset --no-dev-deps; then
+        err "$CRATE did not build with all feature combinations!"
+        exit 1
+    fi
+
     if git tag -l | grep -Fxq "$TAG" ; then
         err "git tag \`$TAG\` already exists"
         exit 1