Fix important bugs (see description)

[JezSonic]

• GitHub: Fix GitHub Actions (64-bits Linux export in build-x11-32 artifact)
• GitHub: Fix GitHub Actions (Linux export file extensions)
• Core: Add mono support in the project for use in the future
• Core: Remove unused Godot Engine plugins
• Core: Fix Discord server invitation
• Core: Add possibility to skip the game intro just by pressing space or enter button on the keyboard
• Core: Add possibility to Quit the credits in any moment
• Core: Add possibility to restart current stage
• Core: Add Discord Game SDK
• Core: Game Over when character falls outside of the stage
• Android/PC: Change UI in the Main Menu (text/email animation is falling off behind game window), Feedback screen and Options to better for small touch screens
• Gameplay: Make red robots doing something bad to player while colliding
• Gameplay: When player falls into the acid... I would give some delay ... in the sense that he falls into it ... and after a second when you see that it is tone ... then game over...
• Graphics: Draw player jump rotation in sprite. Rotating jump in the animation player effect not-well working jump animation flip
• Gameplay: Fix character collisions