Add missing include for specific UE 5.3 builds

[csciguy8]

Came up in the forum here

[1/4] Compile [x64] CesiumGlobeAnchorCustomization.cpp
C:\path\to\project\Plugins\CesiumForUnreal\Source\CesiumEditor\Private\CesiumGlobeAnchorCustomization.cpp(239): error C2664: 'bool IsValid(const UObject *)': cannot convert argument 1 from 'ACesiumGeoreference *' to 'const UObject *'
C:\path\to\project\Plugins\CesiumForUnreal\Source\CesiumEditor\Private\CesiumGlobeAnchorCustomization.cpp(239): note: Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or parenthesized function-style cast
C:\toolchains\unreal\ue-5.3.2-release\Engine\Source\Runtime\CoreUObject\Public\UObject\Object.h(1771): note: see declaration of 'IsValid'
C:\path\to\project\Plugins\CesiumForUnreal\Source\CesiumEditor\Private\CesiumGlobeAnchorCustomization.cpp(239): note: while trying to match the argument list '(ACesiumGeoreference *)'
C:\path\to\project\Plugins\CesiumForUnreal\Source\CesiumEditor\Private\CesiumGlobeAnchorCustomization.cpp(278): error C2664: 'bool IsValid(const UObject *)': cannot convert argument 1 from 'ACesiumGeoreference *' to 'const UObject *'
C:\path\to\project\Plugins\CesiumForUnreal\Source\CesiumEditor\Private\CesiumGlobeAnchorCustomization.cpp(278): note: Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or parenthesized function-style cast
C:\toolchains\unreal\ue-5.3.2-release\Engine\Source\Runtime\CoreUObject\Public\UObject\Object.h(1771): note: see declaration of 'IsValid'
C:\path\to\project\Plugins\CesiumForUnreal\Source\CesiumEditor\Private\CesiumGlobeAnchorCustomization.cpp(278): note: while trying to match the argument list '(ACesiumGeoreference *)'

[csciguy8]

Tried to reproduce locally on Windows 10, UE 5.3.2, but was not successful. Downloading the released plugin and forcing it to build produced a working project.

However, I was able to verify these same problems via Visual Studio's Intellisense. Including this header make the squiggles go away.

[j9liu]

Thanks @csciguy8 !