Meta: Update lint-{clang-format,shell-scripts}.sh to take a list of files

This should speed up pre-commit a bit as only files that are staged will
be processed, and clang-format and shellcheck are only invoked once, not
for every file. When no arguments are given (e.g. on CI), it still uses
'git ls-files'.

Meta/lint-shell-scripts.sh

@@ -10,24 +10,25 @@ if ! command -v shellcheck &>/dev/null ; then
     exit 1
 fi
 
-ERRORS=()
-
-while IFS= read -r f; do
-    if file "$f" | grep --quiet shell; then
-        {
-            shellcheck "$f" && echo -e "[\033[0;32mOK\033[0m]: successfully linted $f"
-        } || {
-            ERRORS+=("$f")
-        }
-    fi
-done < <(git ls-files -- \
-    '*.sh' \
-    ':!:Toolchain' \
-    ':!:Ports' \
-    ':!:Shell/Tests' \
-)
-
-if (( ${#ERRORS[@]} )); then
-    echo "Files failing shellcheck: ${ERRORS[*]}"
-    exit 1
+if [ "$#" -eq "0" ]; then
+    mapfile -t files < <(
+        git ls-files -- \
+            '*.sh' \
+            ':!:Toolchain' \
+            ':!:Ports' \
+            ':!:Shell/Tests'
+    )
+else
+    files=()
+    for file in "$@"; do
+        if [[ "${file}" == *".sh" ]]; then
+            files+=("${file}")
+        fi
+    done
+fi
+
+if (( ${#files[@]} )); then
+    shellcheck "${files[@]}"
+else
+    echo "No .sh files to check."
 fi