Fix selection end column if pruning an empty last column

[tommy9]

Fixes #6181

When a selection of code includes a trailing blank line, the GetSelection method cuts this line and sets the end column to the length of the previous line. However, selections are supposed to be one-based, so we want the length plus 1. E.g. if selecting a line which is just End, we should see start column = 1, end column = 4 which we do if that is the only line selected but if changing the selection to include an extra blank line, the selection gets modified to have end column = 3.

I'm not sure exactly why the last blank line if being pruned but it's not relevant to this issue. Note that only one blank line would be pruned even if there are multiple.

[rubberduck-vba-releasebot]

✅ Build Rubberduck 2.5.9.6311 completed (commit 957fc299d3 by @tommy9)

[codecov]

Codecov Report

Merging #6184 (ce21fbf) into next (9323f70) will increase coverage by 0.24%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             next    #6184      +/-   ##
==========================================
+ Coverage   97.34%   97.58%   +0.24%     
==========================================
  Files           4        4              
  Lines         413      413              
  Branches       28       28              
==========================================
+ Hits          402      403       +1     
  Misses          6        6              
+ Partials        5        4       -1     

see 1 file with indirect coverage changes

[retailcoder]

Thank you so much for taking the time to do this!