feat: entity selector for `autoaim ent`

[ThisAMJ]

e.g.

version 6
start map sp_a2_laser_chaining
0>|||notarget; noclip; setpos 0 952 440
60>>autoaim ent npc_portal_turret_floor 60     // same
+60>>autoaim ent npc_portal_turret_floor[0] 60 // same
+60>>autoaim ent npc_portal_turret_floor[1] 60
+60>>autoaim ent npc_portal_turret_floor[2] 60
+60>>autoaim ent npc_portal_turret_floor[3] 60
+60>>autoaim ent box 60    // same
+60>>autoaim ent box[0] 60 // same
+60>>autoaim ent box[1] 60
+60>>autoaim ent box[2] 60
+60>

[RainbowwPhoenixx]

This should be good, I just want another set of eyes to look at it to make sure there's isn't an obvious mistake. It compiles but I haven't tested because I can't open the game atm.