Replace Exit Sub when converting Subs to Functions

[MDoerner]

Closes #6139

This PR makes the quick fix assign the return value and then exit the function instead of exiting the procedure that gets converted. These two statements are inserted separated by a statement separator instead of doing it on multiple lines to avoid having a separate code path if the Exit Sub is in a single line if statement.

[rubberduck-vba-releasebot]

:white_check_mark: Build Rubberduck 2.5.9.6301 completed (commit https://github.com/rubberduck-vba/Rubberduck/commit/7d29b47459 by @MDoerner)

[codecov[bot]]

Codecov Report

Merging #6171 (6cf1536) into next (877d0f6) will not change coverage. The diff coverage is n/a.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## next #6171 +/- ## ======================================= Coverage 97.58% 97.58% ======================================= Files 4 4 Lines 413 413 Branches 28 28 ======================================= Hits 403 403 Misses 6 6 Partials 4 4 ```