expose annotation styling

[incanus]

Fixes #1734 and allows a workaround for #1814 by exposing the full set of line & fill layout and paint properties to map clients.

Todo:

• Safely query what's set in the passed style (i.e. no .at() directly).
• Render more values.
• Set sane defaults in core for the properties (not necessarily the same as the defaults in LineProperties/FillProperties; for example, shapes shouldn't be black or default to miter line join).
• Test dead code removal from 174fb6b.
• Find a better way to determine fill/line distinction now that the use of the StyleProperties variant is gone (i.e. not this).

[jfirebaugh]

Is there a dependency chain pulling in class_properties.hpp and property_transition.hpp? Those looks like they might be unnecessary. I'm ok with the other includes being "semi-public", in that they are used by iOS but not considered part of the public core GL. These interfaces will probably change a lot with mutable style API and data driven styles.

[jfirebaugh]

@incanus What's the status of this PR?

[jfirebaugh]

Going in the direction of #837 instead.

[incanus]

👍