Scaffold the project: pyproject, gitignore, constants, Doxyfile, README, CI

Task: MIL-002#1
Task: MIL-002#2
Task: MIL-002#3
Task: MIL-002#4
Task: MIL-002#5

src/scoreboard.py

@@ -0,0 +1,7 @@
+"""@file scoreboard.py
+@brief Shows the level and the game over message.
+"""
+
+
+class Scoreboard:
+    """@brief Placeholder, implemented in milestone MIL-006."""