Vertical glyph information access

Hi, currently it is absolutely impossible to get proper vertical text rendering due to the lack of vertical glyph information gainable through the Font API.

Freetype allows one to get glyph information (advance, bearing, etc.) depending on whether the glyph is loaded as horizontal or vertical. This information is key to receiving correct information to render vertical text and would be an absolute must in filling basic information required for more freer, customizable text rendering.

This would finally allow for example Japanese vertical text, and other languages that have vertical versions of writing.

It would also just be great if we could create outlines based on pixel width through the default implementation, again available originally through freetype - doing so without having to go through Text Mesh Pro (which also does not make it possible to set outline width through pixel units)

Unity is an absolutely fabulous engine to work with - just patching up these small holes would allow for a plethora of more freedom.

Reference: https://www.freetype.org/freetype2/docs/tutorial/step2.html