Lint *Error types that don't implement std::error::Error

[jonas-schievink]

I think it would be useful to warn when a type named SomeError does not implement the std::error::Error trait. This is a common annoyance I see in many crates, which leads to the defined error type not being very useful since you can't use it like other error types (you also possibly can't print it if it doesn't impl Display, which is a supertrait of Error).

[clarfonthey]

Additionally, we could lint this for types which are used for associated Error and Err types on traits. For example, someone might have an error type called BadValue and use type Err = BadValue on a FromStr impl, and we'd still want to catch that too.

[alice-i-cecile]

Lending my voice here: I would love to enable this globally for Bevy, after seeing this crop up in bevyengine/bevy#17820