fix(treesitter): support multiple @injection.content captures

Before, only the last capture's range would be counted for injection.
Now all captured ranges will be counted in the ranges array. This is
more intuitive, and also provides a nice solution/alternative to the
"scoped injections" issue.

(cherry picked from commit 8b41df185c)

runtime/lua/vim/treesitter/languagetree.lua

@@ -956,7 +956,9 @@ function LanguageTree:_get_injection(match, metadata)
         local ft = vim.filetype.match({ filename = text })
         lang = ft and resolve_lang(ft)
       elseif name == 'injection.content' then
-        ranges = get_node_ranges(node, self._source, metadata[id], include_children)
+        for _, range in ipairs(get_node_ranges(node, self._source, metadata[id], include_children)) do
+          ranges[#ranges + 1] = range
+        end
       end
     end
   end