Refactor component.rs rename()

[kellpossible]

Hi @juhaku I was attempting to write a documentation comment for rename()

utoipa/utoipa-gen/src/schema/component.rs

Lines 720 to 734 in a1c49de

	fn rename<'a>(
	container_rule: &'a mut Option<Serde>,
	field_rule: &'a mut Option<Serde>,
	rename_op: &impl Fn(&RenameRule) -> String,
	) -> Option<String> {
	let rename = |rule: &mut Serde| match rule {
	Serde::Container(container) => container.rename_all.as_ref().map(rename_op),
	Serde::Value(ref mut value) => mem::take(&mut value.rename),
	};
	field_rule
	.as_mut()
	.and_then(rename)
	.or_else(|| container_rule.as_mut().and_then(rename))
	}

and was struggling, starting to think it could be ripe for refactoring. Perhaps we could transform it/it's uses to use less mut parameters, and make it easier to reason about what's going in/out in a functional style?

[kellpossible]

I guess the point of taking mut is to partly avoid applying the rename more than once, and avoiding taking something by reference by taking it by value from the option? Also with more operations than just rename to come in Serde perhaps the rule scope could be reduced to only accept rename rules?

[kellpossible]

I put some proposed documentation updates in this draft PR https://github.com/juhaku/utoipa/pull/146/files#diff-c2c506c1d61101323c309d3947b6328198fda433dd1be11232fab56d74345b02R762

[juhaku]

Yeah, it indeed is not the easiest function to reason about, and perhaps could be improved a bit.