[NO SQUASH] Update Yeti sprites to fit new style + new animations

[Rusty-Box]

• Update Yeti sprite set
• Update Yeti health icon
• Update Yeti Stalactite sprites for Level Editor
• Code adjustments (help needed)

Code changes required:

• Use of "walking" action must be renamed to "walk" in the code.
• "dizzy" and "busted" action was added for when the yeti is defeated.
  • upon defeat, the yeti will stumble backwards for a bit before falling to the ground, remaining there instead of falling off-screen.
• "fall" action is added for when the Yeti falls or his jump loses altitude.
• Big Snowball projectile spawn position must be adjusted to fit animation.
  • Same may apply to the Bouncy Snowball spawn position
• Upon entering pinch mode, Yeti shall play his "rage" action, beating his chest, to signify to the player that his pinch mode has started.

Minor behavior adjustments (recommandations):

• Big Snowball the Yeti throws should bounce (feels more dynamic that way).
• Reduce amount of Big Snowballs thrown from 3 to 2 on last health (it's odd how he goes from 1 to 3 between second to last and last health).
• In Pinch Mode, instead of walking from one end to the other, Yeti will jump towards the center of the arena, stand still (while the stomp animation plays), allowing for an attack and soon after jump towards the other end of the arena.
• Slightly reduce delay between transitions
  - pinch mode rage -> snowball throw
  - landing on platform -> snowball throw
  - delay between individual snowball throws

FIXME:

• Yeti does not play "gna" sound when leaping in to thei air, right before the stomp
• Big Snowballs should hurt Tux and break if "crushed" but not kill Tux

[tobbi]

/Users/runner/work/supertux/supertux/src/badguy/yeti.cpp:576:13: error: 4 enumeration values not handled in switch: 'ANNOUNCE', 'FALL', 'IDLE'... [-Werror,-Wswitch]
    switch (m_state) {
            ^~~~~~~
/Users/runner/work/supertux/supertux/src/badguy/yeti.cpp:576:13: note: add missing switch cases
    switch (m_state) {