[Diagnostics] Fix range of fix-its in verify mode

[omochi]

This PR fix fix-its range of fix-its range in verify mode.

Current:

$ swift -frontend -typecheck -verify a.swift
a.swift:2:89: error: expected no fix-its; actual fix-it seen: {{14-14=else }}
  guard true { return } // unexpected-error {{expected 'else' after 'guard' condition}} {{none}}
                                                                                        ^~~~~~~
                                                                                        {{14-14=else }}

A range of fix-its is {{none}.

Patched:

$ swift -frontend -typecheck -verify a.swift
a.swift:2:89: error: expected no fix-its; actual fix-it seen: {{14-14=else }}
  guard true { return } // unexpected-error {{expected 'else' after 'guard' condition}} {{none}}
                                                                                        ^~~~~~~~
                                                                                        {{14-14=else }}

A range of fix-its is {{none}}.

This error is small for human.
But it's important when we use -verify-apply-fixes.

I also added test case for -verify-apply-fixes.
I couldn't find one already exists.

@gregomni @jrose-apple Please review this.
Original code is introduced in #674 .

[rintaro]

@swift-ci Please smoke test

[omochi]

@rintaro Thank you for review!