Lint for &Dom<T> arguments

[jdm]

There's no benefit to using &Dom<T> instead of &T function arguments. However, when we tried to add that lint in #25354, we discovered

servo/components/script/dom/servoparser/mod.rs

Line 990 in 3b44218

type Handle = Dom<Node>;

and

servo/components/script/dom/servoparser/mod.rs

Line 996 in 3b44218

fn get_template_contents(&mut self, target: &Dom<Node>) -> Dom<Node> {

which make it challenging to change.

[highfive]

cc @wafflespeanut

[jdm]

I wonder if TreeSink could have a second associated type for HandleArg with a constraint that allows converting from Handle to HandleArg.