[google_maps_flutter] Add marker clustering support - iOS implementation

[jokerttu]

This PR introduces support for marker clustering for iOS platform

An example usabe is available in the example application at ./packages/google_maps_flutter/google_maps_flutter_ios/example/ios12 on the page Manage clustering

This is prequel PR for: https://github.com/flutter/packages/pull/4319 and sequel PR for: https://github.com/flutter/packages/pull/6158

Containing only changes to google_maps_flutter_ios package.

Follow up PR will hold the app-facing plugin implementation.

Linked issue: https://github.com/flutter/flutter/issues/26863

Pre-launch Checklist

• [x] I read the Contributor Guide and followed the process outlined there for submitting PRs.
• [x] I read the Tree Hygiene wiki page, which explains my responsibilities.
• [x] I read and followed the relevant style guides and ran the auto-formatter. (Unlike the flutter/flutter repo, the flutter/packages repo does use dart format.)
• [x] I signed the CLA.
• [x] The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• [x] I linked to at least one issue that this PR fixes in the description above.
• [x] I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or this PR is exempt from version changes.
• [x] I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style.
• [x] I updated/added relevant documentation (doc comments with ///).
• [x] I added new tests to check the change I am making, or this PR is test-exempt.
• [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

[jokerttu]

@hellohuanlin

can you add some unit tests on native side?

Added some native unit tests

[jmagman]

@jokerttu is this ready for re-review?

[jokerttu]

@jokerttu is this ready for re-review?

@jmagman not yet, this is waiting new release of Google-Maps-iOS-Utils library to have support latest Google Maps SDK versions. See discussion here: https://github.com/flutter/packages/pull/6186#discussion_r1581115795

[stuartmorgan-g]

FYI I have raised the blocking issue internally with the Google Maps team.

[stuartmorgan-g]

Update from triage: I haven't heard anything yet on when the utils SDK will be usable for us.

[Rexios80]

It looks like the iOS utils pod might be updated enough to land this. Worth checking out: https://github.com/googlemaps/google-maps-ios-utils/issues/473#issuecomment-2261690953

[jokerttu]

As version 5.0.0 and version 6.0.0 for Google-Maps-iOS-Utils has been published, I am able to continue with this. Meanwhile the package has been migrated to pigeon, so this needs now a bit more changes than version number...

[jokerttu]

@stuartmorgan this is again ready for review.

Updated version dependency for Google-Maps-iOS-Utils: s.dependency 'Google-Maps-iOS-Utils', '>= 5.0.0', '< 7.0.0' ios14 uses version 5.0.0 for GoogleMaps Sdk version 8.x ios15 uses version 6.0.0 for GoogleMaps Sdk version 9.x

Migrated to pigeon messaging

[jokerttu]

@stuartmorgan Fixed the issues mentioned in the review. Rebased and fixed conflicts with heatmap support.

[auto-submit[bot]]

auto label is removed for flutter/packages/6186, due to This PR has not met approval requirements for merging. Changes were requested by {stuartmorgan}, please make the needed changes and resubmit this PR. The PR author is a member of flutter-hackers and needs 0 more review(s) in order to merge this PR.

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[jokerttu]

@stuartmorgan seems like I need separate approval from you before I can add autosubmit label.