fix(3984): Retain simply qualified name of throwable type

[slarse]

Fix #554

This PR fixes a problem where the UnusedThrowableProcessor always creates a fully qualified name for the throwable, even when a simply qualified name is used initially. I.e. the repair looks like so:

-new IllegalArgumentException();
+throw new java.lang.IllegalArgumentException();

With this fix, the repair looks as intended:

-new IllegalArgumentException();
+throw new IllegalArgumentException();

In doing the exact match test to check that the printed reference is indeed simply qualified, I also discovered that comments on the thrown expression must be moved to the CtThrow, otherwise they are printed like this before the semicolon:

throw new IllegalArgumentException()// here's a comment
;

And that just looks very strange.

[fermadeiral]

Nice fix, thank you @slarse.