ci: Use python to extract JS snippets from style guide

The job that lints code snippets in the style guide only runs
when either the documentation or the linting rules are changed.

Because of that it went unnoticed that the awk tool it uses to
extract the snippets is no longer available since the CI image
was rebased to F42.

Given that awk is awkward anyway, use the opportunity to rewrite the
snippet extraction in python instead of adding awk back to the image.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3694>

.gitlab-ci/eslint-coding-style.sh

@@ -6,36 +6,36 @@ trap "rm -rf $OUTDIR" EXIT
 
 # Turn ```javascript``` code snippets in the
 # style guide into .js files in $OUTDIR
-awk --assign dir=$OUTDIR -- '
+cat <<'EOF' | python3 - docs/js-coding-style.md $OUTDIR
-  BEGIN {
+import sys
-    do_print = 0;
+import re
-    cur = 0;
-  }
 
-  # end of code snippet
+def extract_js_snippets(input_file, output_dir):
-  /```$/ {
+    with open(input_file, 'r') as file:
-    do_print = 0;
+        content = file.read()
-    cur++;
-  }
 
-  do_print {
+    # Find all JavaScript code blocks using regex
-    # remove one level of indent
+    js_blocks = re.findall(r'```javascript\n(.*?)\n?```', content, flags=re.DOTALL)
-    sub("    ","")
 
-    # the following are class snippets, turn them
+    for i, (match) in enumerate(js_blocks):
+        js_code = match
+
+        # Remove one level of indent
+        js_code = re.sub(r'^ {4}', '', js_code, flags=re.MULTILINE)
+
+        # The following are class snippets, turn them
         # into functions to not confuse eslint
-    sub("moveActor","function moveActor")
+        js_code = re.sub(r'^moveActor', 'function moveActor', js_code)
-    sub("desaturateActor","function desaturateActor")
+        js_code = re.sub(r'^desaturateActor', 'function desaturateActor', js_code)
 
-    # finally, append to the currently generated .js file
+        # Finally, create a .js file in the output directory
-    print >> dir "/" cur ".js";
+        output_filename = f'{output_dir}/{i}.js'
-  }
+        with open(output_filename, 'w') as out_file:
+            out_file.write(f'{js_code}\n')
 
-  # start of code snippet
+input_file, output_dir = sys.argv[1:]
-  /```javascript$/ {
+extract_js_snippets(input_file, output_dir)
-    do_print = 1;
+EOF
-  }
-' docs/js-coding-style.md
 
 eslint \
   --rule 'no-undef: off' \