[GHA] Unacceptable language check

# Motivation

Next up replacing part of our soundness script that checked for unacceptable language.

# Modification

This PR adds a new GH action that checks for unacceptable language.

# Result

One more script replaced

.github/workflows/pull_requests.yml

@@ -68,4 +68,33 @@ jobs:
 
         for target in "${targets[@]}"; do
           swift package plugin generate-documentation --target "$target" --warnings-as-errors --analyze --level detailed
-        done
+        done
+
+  acceptable-language-check:
+    name: Acceptable language check
+    runs-on: ubuntu-latest
+    timeout-minutes: 1
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v4
+    - name: Run acceptable language check
+      shell: bash
+      run: |
+        set -euo pipefail
+
+        log() { printf -- "** %s\n" "$*" >&2; }
+        error() { printf -- "** ERROR: %s\n" "$*" >&2; }
+        fatal() { error "$@"; exit 1; }
+
+        UNACCEPTABLE_WORDS="blacklist|whitelist|slave|master|sane|sanity|insane|insanity|kill|killed|killing|hang|hung|hanged|hanging"
+
+        log "Checking for unacceptable language..."
+        PATHS_WITH_UNACCEPTABLE_LANGUAGE=$(git grep \
+          -l -F -w -E ${UNACCEPTABLE_WORDS} \
+        ) || true | /usr/bin/paste -s -d " " -
+
+        if [ -n "${PATHS_WITH_UNACCEPTABLE_LANGUAGE}" ]; then
+          fatal "❌ Found unacceptable language in files: ${PATHS_WITH_UNACCEPTABLE_LANGUAGE}."
+        fi
+
+        log "✅ Found no unacceptable language."