fix infinite loop caused by weird addons

fix null ent error

CTakeDamageInfo:Set/GetWeapon was added in dev branch version 2025.01.15

idk what the implications of this are yet but for now all clhr does with it is preserve its value for client-registered hits (like with the other properties of CTakeDamageInfo)

fixed a lua error that happens when shot target is somehow behind the shooter

- added new hooks CLHR_PreShouldApplyToBullet(ply, data) and CLHR_PostShouldApplyToBullet(ply, trace, dmginfo) for compatibility purposes
- fixed a potential exploit with clhr_subtick that lets cheaters set whatever shootpos they want

- added a new cvar clhr_subtick which simulates subtick hitreg https://youtu.be/rCLgx5wj4zk (please don't use this feature in public servers)
- tried to fix some weird bug with zero-damage arccw weapons

fixed a lua error that happens when the first ever hit message that the server receives from the client arrived too early

instead of suppressing the shot entirely, now only disables lag compensation for shots that have a tick count that's lower than the last shot's tick count

- tolerance checks now take client interp settings into account
- tweaked some clhr_printshots debug messages

- added a new cvar clhr_nofirebulletsincallback which stops Entity:FireBullets from firing a new bullet when executing the callback function of a client-registered hit
- added an option to set a CLHR_Disabled field in a swep table to disable clientside hitreg for certain weapons
- shotgun hits are now merged into a single net message instead of one for each pellet
- fixed EntityFireBullets hooks with non-string identifiers not being run