Print console warning for maps that use RTL text without RTL text plugin

[ChrisLoer]

When we added the RTL text plugin, we wanted to make it have no overhead/configuration complexity for people who didn't need it, on the assumption that motivated users would find the plugin and turn it on. However, if a developer wants to make a map that uses local language labels around the world, they may not even realize that RTL text isn't displaying correctly.

As a stop-gap, I think we should just add a console warning whenever we render text that requires the RTL plugin and it's not enabled. The warning should be minimally disruptive/almost invisible to users, but a map developer is pretty likely to see it and it's an easily actionable error message.