Add code fix for double literal without dot

[amcasey]

It's very easy to write 2 when you mean 2.. Offer a code fix.

[amcasey]

I don't really care whether we merge this. I make this mistake pretty regularly in Q#, but I mostly implemented it to practice writing rust without copilot.

With all the time in the world, I'd probably experiment with having type inference infer either Int or Double for integer literals, depending on the context. In such a world, we might want a suffix to force the literal to Int, but the only place I can think of where both are allowed and the difference matters is division.

[amcasey]

When we switched from one edit to two, the updated text became less meaningful as confirmation that the action was behaving correctly, so now we check the locations of the edits too.