feat(api): nvim_set_hl can set "font" #37668

Problem: Cannot set highlight group fonts via API, only via :highlight
command.

Solution: Add font parameter in nvim_set_hl().

runtime/lua/vim/_meta/api_keysets.lua

@@ -337,6 +337,7 @@ error('Cannot require a meta file')
 --- @field force? boolean
 --- @field update? boolean
 --- @field url? string
+--- @field font? string
 
 --- @class vim.api.keyset.highlight_cterm
 --- @field bold? boolean