Extract resource handling to UnityResource
Add API header resource helpers
Fix UnityVersion ToString() when Min == Max
Replace fixed list of Il2Cpp header reserved names with parsed names from actual selected headers (solves TypeInfo/MemberInfo problems in 5.3.0-5.3.4 (metadata v16-20))
Use CppDeclarationGenerator when initializing CppTypeCollection to ensure all Il2Cpp header symbols are reserved
Process API headers in CppTypeCollection.FromUnityHeaders
Move #define IS_32BIT handling to UnityHeaders
Update tests