[Core] Adds missing quantity count to charutils getItemCount

[LoxleyXI]

I affirm:

• [x] I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
• [x] I understand I should leave resolving conversations to the LandSandBoat team so that reviewers won't miss what was said.
• [x] I have read and understood the Contributing Guide and the Code of Conduct.
• [x] I have tested my code and the things my code has changed since the last commit in the PR and will test after any later commits.

What does this pull request do?

getItemCount isn't factoring in quantity, eg. player:getItemCount(1455) returns 1 if a player has 1 Byne Bill x99. This change fixes the issue.

Steps to test these changes

Tested with stacking and non-stacking items and if player has no matching items.

[Xaver-DaRed]

Nothing like having 5 functions with the same name