Possible memory leak in iOS

[Jasonvdb]

Not 100% certain this is an issue and no urgent fix or investigation required now but creating this ticket in case this causes a problem later.

After calling an rgb function from Swift code and using the pointer in CResultString to create Swift string, that data is only copied and the original most likely is never being released from memory on the rust side. Usually in a C library there will be an additional function to call to explicitly release the result from memory once the Swift code is done copying it.