Improve error message for lifetime error with dyn Trait

[ohadravid]

This is an attempt to improve the errors in cases like #54779.
Because SomeType<dyn OtherTrait> and impl SomeTrait for dyn OtherTrait are implicitly dyn OtherTrait+ 'static, it can be quite confusing as to why things don't work. (I originally stumbled upon this because of this question - playground link).

This PR tries to handle those two cases, by:

1. Pointing at the requiring implementation.
2. Suggesting the dyn Trait + '_, like impl Trait does.

There seems to be a lot of places to handle these errors, and I can't really say I fully understand the sub/sup/origin region stuff, but I got it to mostly work and wanted to get some feedback on what should I do next (and if! I'm not sure if this is the best idea/approach).
Also there are almost no existing examples in the test suite which seems to cover this usecase.

Most noticeably, I think that if you already specify + 'static or some other lifetime, the suggestion will be both useless and incorrect, and if you have Box<&dyn Trait> you'll get Box<&dyn Trait + '_> which isn't really correct (should be &(dyn Trait + '_)).

r? @estebank

[estebank]

I don't have time to do an in-depth review right now, but we should try to come up with a different way of doing this. Fiddling with the textual representation of the code is a recipe for pain later on. It produces output that isn't always correct (like the problem with the missing parens and some incorrect suggestions I noticed below), and is brittle and affected by whitespace. I'll take another look later to see if I can have more actionable feedback on what to do instead.

[bors]

☔ The latest upstream changes (presumably #67495) made this pull request unmergeable. Please resolve the merge conflicts.

[joelpalmer]

Ping from Triage: Any updates @ohadravid or @estebank?

[ohadravid]

@joelpalmer I'll close this and try something more minimal in a different PR