CI: Speed up static checks by checking only changed files

- file_format, header_guards and clang-format benefit from this short list.
- dotnet-format, Python and JS checks don't, but they're only relevant for
  PRs changing a specific set of files, so we skip them when those files
  aren't modified.

The logic to get changed files only works reliably for:
- Pull request events
- Non-force pushed push events

So when force pushing a branch in your fork, or creating a new branch,
it will still scan all files as fallback.

Upgraded CI runner to Ubuntu 22.04 so we get clang-format 14 out of the box,
so we don't need to install a custom version (saves ~15 s). We also cache
the APT dependencies to speed up the build and avoid flaky Ubuntu/Microsoft
repos.

misc/scripts/clang_format.sh

@@ -5,15 +5,22 @@
 
 set -uo pipefail
 
-# Loops through all code files tracked by Git.
-git ls-files -- '*.c' '*.h' '*.cpp' '*.hpp' '*.cc' '*.hh' '*.cxx' '*.m' '*.mm' '*.inc' '*.java' '*.glsl' \
+if [ $# -eq 0 ]; then
+    # Loop through all code files tracked by Git.
+    files=$(git ls-files -- '*.c' '*.h' '*.cpp' '*.hpp' '*.cc' '*.hh' '*.cxx' '*.m' '*.mm' '*.inc' '*.java' '*.glsl' \
                 ':!:.git/*' ':!:thirdparty/*' ':!:*/thirdparty/*' ':!:platform/android/java/lib/src/com/google/*' \
-                ':!:*-so_wrap.*' ':!:tests/python_build/*' |
-while read -r f; do
-    # Run clang-format.
-    clang-format --Wno-error=unknown -i "$f"
+                ':!:*-so_wrap.*' ':!:tests/python_build/*')
+else
+    # $1 should be a file listing file paths to process. Used in CI.
+    files=$(cat "$1" | grep -v "thirdparty/" | grep -E "\.(c|h|cpp|hpp|cc|hh|cxx|m|mm|inc|java|glsl)$" | grep -v "platform/android/java/lib/src/com/google/" | grep -v "\-so_wrap\." | grep -v "tests/python_build/")
+fi
 
-    # Fix copyright headers, but not all files get them.
+if [ ! -z "$files" ]; then
+    clang-format --Wno-error=unknown -i $files
+fi
+
+# Fix copyright headers, but not all files get them.
+for f in $files; do
     if [[ "$f" == *"inc" ]]; then
         continue
     elif [[ "$f" == *"glsl" ]]; then