Rule Request: Verify that #imageLiteral references existing asset

New rule request

1) Why should this rule be added? Share links to existing discussion about what
the community thinks about this.

Referencing a non-existing asset with #imageLiteral() will result in a crash at runtime. As seen e.g. here and as experienced by me today, it's very surprising that #imageLiteral() is not checked by the Swift compiler in the first place. I think the next best thing after that would be to have an error lint about it, which is why I created this suggestion ☺️

2) Provide several examples of what would and wouldn't trigger violations.

The following code would trigger a violation:

#imageLiteral(resourceNamed: "DoesNotExists")

The following code would not trigger a violation:

#imageLiteral(resourceNamed: "DoesExists")

3) Should the rule be configurable, if so what parameters should be configurable?

No.

4) Should the rule be opt-in or enabled by default? Why?
See README.md for guidelines on when to mark a rule as opt-in.

I think the rule should be enabled by default (unless the implementation turns out to be slow) since it's a problem that will cause a crash at runtime, and I don't see that there will be any false positives.

I'd be willing to help contribute code for this ☺️

Start with README.md and its opt-in-rules guidance, then review the linked discussion for prior context. Use the provided existing and missing #imageLiteral(resourceNamed:) examples as acceptance cases; done means the missing asset is reported while the existing asset is not.