feat: snippets for embedded languages

[sghng]

This resolves #1679.

[Saghen]

Tricky part is that treesitter parsers don't map 1 to 1 with neovim filetypes. I maintain a list of mappings in blink.pairs, derived from nvim-treesitter: https://github.com/Saghen/blink.pairs/blob/main/lua/blink/pairs/context/treesitter.lua#L7. I think we should provide a top level require('blink.cmp').language_at_position(cursor) that does this and performs the mapping.

[sghng]

Tricky part is that treesitter parsers don't map 1 to 1 with neovim filetypes. I maintain a list of mappings in blink.pairs, derived from nvim-treesitter: https://github.com/Saghen/blink.pairs/blob/main/lua/blink/pairs/context/treesitter.lua#L7. I think we should provide a top level require('blink.cmp').language_at_position(cursor) that does this and performs the mapping.

Looks awesome, I can rewrite my PR when this util is added