ref!(math-renderer): modularize image generation to make way for typst

[benlubas]

More or less what it says on the tin.

Extracts the latex specific image generation code into it's own module, and provides that module as configuration to the (now called) math-renderer. This opens up the possibility of other math renderers, the most notable being typst.

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Down the road, the norg file format will hopefully have some standard way of specifying the math language, and then this module can be reworked again to take that into account (and possibly render typst and latex in the same document). But for now, user configuration that allows rendering either latex or typst seems like a good starting point.

[vhyrro]

question: isn't this a breaking change, given the module name is now different?

[benlubas]

yes, but the other one hasn't released yet.. and I already forgot that latex rendering existed before my PR to make it better lol.

Yea this should maybe be marked breaking