[2.0] Knockback calculation and entity damaging generally is broken

[KCodeYT]

Entity knockback:
Player1 hits Player2 and Player2 is getting knockback in the same direction everytime even the Player1 isnt looking in the direction.

Entity Damaging:
You cant damage entitys (not players) if you are standing 2 blocks or more away from them

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[joserobjr]

Additionally, you might get invulnerable to all damages when you are standing on a slime block, i think the if slime check should be inside the if damage cause is fall, I was going to test it yesterday but I ran out of time.

https://github.com/NukkitX/Nukkit/blob/abd10c1c7ce8a4cbdb5e0c6bef0813f7248956e0/src/main/java/cn/nukkit/player/Player.java#L3631-L3639

[joserobjr]

Entity Damaging:
You cant damage entitys (not players) if you are standing 2 blocks or more away from them

I think I found the issue:

(That was only a spare click, I guess attackTime isn't updating due to the entity not ticking)