[ios] Adds the ability to get selection events for shape annotations

[csmulhern]

This should not break any existing behavior, as the implementation makes shapes default to enabled = NO.

[1ec5]

Thank you for this PR – this is absolutely important functionality to have. I think we’ll ultimately want to combine your SDK-level changes with #5165, which avoids having to pull in boost::geometry. (With #5110 and #352, we finally have a feature index that can be used for everything, not just points and not just annotations.) I’m currently focusing on the 3.3.0 release right now, but I’ll pick up #5165 again right afterwards so we can get rid of the existing mbgl code that’s limited to points.

/cc @jfirebaugh @boundsj @tobrun

[1ec5]

#5165 landed, so now we can implement a queryShapeAnnotations() that calls queryRenderedFeatures() – no custom querying logic is needed anymore. Unlike in queryPointAnnotations(), the call to queryRenderedFeatures() will need to pass in the layer IDs of all the shape annotation layers.

[1ec5]

This was implemented in #9984 with the approach described in #5502 (comment). Thank you for this early iteration, though!