Eliminate Source#on{Add,Remove}(map)

[jfirebaugh]

The main use of on{Add,Remove}(map) in source subclasses is to store a reference to the map for later use. This introduces both statefulness (certain source operations work only after onAdd has been called) and tight coupling between a source and the map.

Instead, sources should be passed the things to which they need access as parameters to the relevant methods.

Ref #3255 (comment)

[mourner]

Instead, sources should be passed the things to which they need access as parameters to the relevant methods.

It's not always possible directly — e.g. map.getSource('image').setCoordinates(coords), where setCoordinates depends on map transform to recalculate coords. We'll have to pass a map reference to methods like loadTile.

[jfirebaugh]

In that case, setCoordinates should be a simple setter, deferring the calculations that require a transform until a later time. Ideally loadTile should not take a map reference but rather a reference to the transform or whatever other state is needed, so that there isn't a circular dependency between map and sources.

[lucaswoj]

Thank you for opening! This will go hand-in-hand with #3186.