CI: Partially sync workflows and actions with 3.x branch

Stick to `ubuntu:20.04` runners for now, as porting to newer ones implies
fixing a number of compilation warnings which may not be worth the trouble
for an EOL branch.

misc/scripts/check_ci_log.py

@@ -0,0 +1,53 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+import sys
+
+if len(sys.argv) < 2:
+    print("ERROR: You must run program with file name as argument.")
+    sys.exit(1)
+
+fname = sys.argv[1]
+
+fileread = open(fname.strip(), "r")
+file_contents = fileread.read()
+
+# If find "ERROR: AddressSanitizer:", then happens invalid read or write
+# This is critical bug, so we need to fix this as fast as possible
+
+if file_contents.find("ERROR: AddressSanitizer:") != -1:
+    print("FATAL ERROR: An incorrectly used memory was found.")
+    sys.exit(1)
+
+# There is also possible, that program crashed with or without backtrace.
+
+if (
+    file_contents.find("Program crashed with signal") != -1
+    or file_contents.find("Dumping the backtrace") != -1
+    or file_contents.find("Segmentation fault (core dumped)") != -1
+    or file_contents.find("Aborted (core dumped)") != -1
+    or file_contents.find("terminate called without an active exception") != -1
+):
+    print("FATAL ERROR: Godot has been crashed.")
+    sys.exit(1)
+
+# Finding memory leaks in Godot is quite difficult, because we need to take into
+# account leaks also in external libraries. They are usually provided without
+# debugging symbols, so the leak report from it usually has only 2/3 lines,
+# so searching for 5 element - "#4 0x" - should correctly detect the vast
+# majority of memory leaks
+
+if file_contents.find("ERROR: LeakSanitizer:") != -1:
+    if file_contents.find("#4 0x") != -1:
+        print("ERROR: Memory leak was found")
+        sys.exit(1)
+
+# It may happen that Godot detects leaking nodes/resources and removes them, so
+# this possibility should also be handled as a potential error, even if
+# LeakSanitizer doesn't report anything
+
+if file_contents.find("ObjectDB instances leaked at exit") != -1:
+    print("ERROR: Memory leak was found")
+    sys.exit(1)
+
+sys.exit(0)