[google_maps_flutter_web] Allow marker position updates

[AsturaPhoenix]

Unconditionally convert the current marker position in convert.dart:_markerOptionsFromMarker, to allow for position updates.

Also adds position changes to marker_test.dart/MarkerController/update and markers_test.dart/MarkersController/changeMarkers. The MarkersController case is fixed by this patch.

Issue: flutter/flutter#83467

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[stuartmorgan-g]

Thanks for the contribution! Could you merge in the latest main? This is branched from a version older than the last update to our infrastructure tokens, so most of the CI is unable to run.

[AsturaPhoenix]

Done; please let me know if further action is required from me. I'm not familiar with these tests, but the failing test looks like it can't find the compass button on iOS. I don't have an iOS test setup yet, and this change was limited to the web plugin.

[AsturaPhoenix]

Looks like that test may have been reverted. Rebasing and rerunning.

[stuartmorgan-g]

@ditman Ping on this review.

[stuartmorgan-g]

We've just completed the migration of the plugin code to the flutter/packages repository, as described in https://flutter.dev/go/flutter-plugins-repo-migration, and this repository is now being archived. Unfortunately that means that all in-progress PRs here must be moved to flutter/packages.

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