[MDB IGNORE] Make /obj/item/stamp abstract, create proper granted stamp subtype (#94139)

## About The Pull Request

There is technically an `/obj/item/stamp/granted` in that one traitor
objective refers to it and tries to override a proc on it thus making it
a valid type, but not really. This changes the base `/obj/item/stamp`
from being the granted stamp to being an abstract type, and creates a
proper subtype for the granted stamp.

## Why It's Good For The Game

Base types being concrete outside of scenarios where its intuitive are
very annoying

## Changelog
🆑
code: makes /obj/item/stamp abstract, creates /obj/item/stamp/granted
/🆑

tools/UpdatePaths/Scripts/94139_granted_stamp.txt

@@ -0,0 +1 @@
+/obj/item/stamp : /obj/item/stamp/granted{@OLD}