all: Adjust UseStateForUnknown plan modifiers to preserve known null state values (#1161) (#1194)

* apply fix to string plan modifier and shared tests

* sets

* list

* map

* object

* numbers, floats, and ints

* bool

* dynamics

* add changelog

Author: austinvalle

.changes/unreleased/BUG FIXES-20250612-115411.yaml

@@ -0,0 +1,5 @@
+kind: BUG FIXES
+body: 'all: Fixed bug with `UseStateForUnknown` where known null state values were not preserved during update plans.'
+time: 2025-06-12T11:54:11.818923-04:00
+custom:
+    Issue: "1117"