89ce6055a6
A couple string constants had been incorrectly declared `const NSString*` rather than `NSString* const`. The former is a pointer to an immutable string, but (a) the pointer can be reassigned and (b) the default NSString implementation is immutable. The latter is an immutable pointer to a string, which is what we want, since we don't want developers reassinging our constants to other values. Also updates an identifier name to pass lint rules. No changes to tests since this is "tested" by the compiler. [C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style