Remove SM 1.9 checks and make use of GivePlayerItem in > SM 1.11

- Sourcemod 1.9 and 1.8 checks are too ancient to keep supporting/checking for. (I'm not touching "includes" for this as official files still do check as well)
- Replaced USE_GIVEPLAYERITEM setting or exact SM 1.11 check with a proper check for the version GiveNamedItem was fixed in.

Author: SirPlease