Default prop values from host elements

[itsdouges]

From https://github.com/try-triplex/triplex/issues/176 we now have default props expressed in the editor from first party custom components (provider / component / props). What's missing is default props from host elements. Generally this information isn't available but Three.js host elements generally have JSDoc mentioning what the default is, so we could use that.

Bit of explore / make here.