Honor clickable for Markers in Google Maps

[seadowg]

Closes #7313

Why is this the best possible solution? Were any other approaches considered?

Google Maps doesn't offer a way to make markers non-clickable so we need to determine whether we should call the feature listener or the map click listener when a marker click occurs here. That does mean that trying to add a point or a line/shape vertex by clicking on a marker will always add the new feature at exactly the same location: that could be considered feature.

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

Should just fix the issue! As mentioned above, clicking on a marker will always count as a click on the exact point of the marker which means that new features being added via clicks will snap to it.

Before submitting this PR, please make sure you have:

• added or modified tests for any new or changed behavior
• run ./gradlew connectedAndroidTest (or ./gradlew testLab) and confirmed all checks still pass
• added a comment above any new strings describing it for translators
• added any new strings with date formatting to DateFormatsTest
• verified that any code or assets from external sources are properly credited in comments and/or in the about file.
• verified that any new UI elements use theme colors. UI Components Style guidelines

[grzesiek2010]

This can be private.

[seadowg]

I think I'd prefer to leave it private like the other methods on this class. The outer class can access it because Java (if it was Kotlin we'd have a file private class instead), but it makes more sense to have the inner class be private to the outer class and then have the methods used by things outside the inner class be public.