Projectile implementation + Ranger character class

[NancokPS2]

Testing:
Currently projectiles can be tested by choosing the Ranger class and trying both of its skills.

Planned implementation:

1. Projectiles work as normal physics objects in the server.
2. When a projectile is fired by a player (server confirmed). The server sends information to the client about the initial position and direction of the projectile as well as other relevant information for it's expected movement.
3. The client's component creates and starts moving the projectile with physics enabled client-side, this is purely visual and it is meant to provide better feedback for the player. This projectile also has no effect when it collides with something and simply dissapears.
4. If the projectile has a collision animation, once it collides with something. The server sends a PackedVector2Array with the locations where the projectile collided (it is an Array for cases where a projectile can pierce) to the client. The client is then responsible for playing the corresponding animations in each of those locations. This helps with feedback as to what was actually hit in cases where the movement of the projectile does not match the server.
5. All other feedback like damage dealt or application of status effects are carried out by their respective components as usual.

Projectile features:

• Optional skill_class property which makes them use a skill with said class on any hit targets
• Optional collision scene property, the defined scene will be added on the projectile's location on impact. This is meant to allow to create a PackedScene with particles or some other effects.
• New scripts may be created for other projectiles that override the projectile's get_motion() function. This allows changing how the projectile moves and allows things like homing projectiles.
• Lifespan that automatically deletes the projectile after a given time, should it not collide with anything that would cause it to be destroyed sooner.
• Projectiles can store PackedScenes to spawn when they collide with something, if the root node of the PackedScene is a CPU/GPUParticles2D node, it is set to emitting upon being added to the scene.
• Can define a limit of instances per entity. This means that a projectile has a limit of 10, a player cannot fire more than 10 of those projectiles at a time (the oldest one is deleted). These limits are per entity and per projectile class. For example, 2 ranger players can spawn a maximum of 20 arrows and 8 traps if both of them spam both skills.

Screenshot (because)

Ranger:
The only class that uses projectiles so far, uses a skill to fire arrows until ranged weapons get added. Can also set a trap for enemies to stumble into that lasts 2 minutes, only 4 can exist at a time.

TODO:

• [x] Revert commits for entity approach
• [x] Re-scale sprites for other projectiles
• [x] Create a skill that uses projectiles
• [x] Make collision locations be synched to clients
• [x] Create projectiles for testing
• [x] Improve how projectiles are synched to nearby entities.

Closes: #200

[NancokPS2]

Due to move_and_collide() not working currently, we may need a different approach in the meantime.

[NancokPS2]

idk if rebasing is meant to make 15 instant commits, but it did

[jonathaneeckhout]

Tested and works fine.

I had some comments to polish it, placing it another issue: https://github.com/jonathaneeckhout/jdungeon/issues/226