Makes setURL method on MLNImageSource public

[manuelroth]

This PR makes the setURL method on the MLNImageSource public. This is required to be able to dynamically update the url of an existing image source. The Android SDK already provides such a method (see setUri for more details). Until now this use case could only be addressed by creating a new source when ever the url changed and deleting the "old" source which resulted in bad performance of the app. The setURL method would greatly improve the implementation of this use case.

Please let me know if I can improve anything. I am not an Objective-C developer. Therefore any hints on improvements are greatly appreciated.

[github-actions]

Bloaty Results (iOS) 🐋

Compared to main

    FILE SIZE        VM SIZE    
 --------------  -------------- 
  [ = ]       0  [ = ]       0    TOTAL

Full report: https://maplibre-native.s3.eu-central-1.amazonaws.com/bloaty-results-ios/pr-2197-compared-to-main.txt

[louwers]

Thanks for your contribution. :)

Will be included in the next release along with your other PR. Let me know if you need it soon, then I can push out a release.

[manuelroth]

Thank you very much for reviewing my PR. It is awesome to contribute in this way. I really appreciate it. Unfortunately we are currently blocked from upgrading to MapLibre v6 by this issue reported by my teammate: #2189. Would it be feasible to create another v5 release with this changes in addition to a v6 release?- So we could already take advantage of this change while a solution for the issue #2189 can be found. If its too much effort it is also fine. Of course we want to upgrade to v6 as soon as possible, but for the moment we unfortunately cannot.