Feature request: port MetaPost related methods from ConTeXt

[jemmybutton]

One useful function missing from LuaLaTeX's implementation of MetaPost+MetaFun via luamplib is outlinetext. It relies on ConTeXt's font loading system to get glyph outlines, and, it seems like, it would be logical to have this functionality in luaotfload as well. For glyph outlines themselves it seems to be a matter of just one function, fonts.metapost.paths https://github.com/contextgarden/context/blob/cbad4115844551c827a215ea8dc8ec3e4a1a40af/tex/context/base/mkiv/font-mps.lua#L66 with everything else required already present in luaotfload (see this example).
Implementing even simply the outlines for separate glyphs would be a great improvement over MetaPost's glyph function which doesn't seem to work nicely with .otf fonts and such.
What it would take to port everything else required for outlinetext to work, and what portion of it is has anything to do with ConTeXt's fontloader and luaotfload I'm not yet sure though.