Fix trimming of whitespace when table is wrapped

[SteveL-MSFT]

PR Summary

The original algorithm used math to determine the last column that had content, however, it didn't work correctly when -Wrap is used with Format-Table. Fix is to use a simpler brute force approach by checking it cell in the table to determine if it's the last column in that row with content so that we trim trailing whitespace correctly.

Fix #7179

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[anmenaga]

3 empty lines (here and in 2 other cases below) - are they necessary ?

[SteveL-MSFT]

It annoys me, too, but that is currently what PowerShell outputs. We should probably look into that as a separate issue. Created #7186

[iSazonov]

Seems we catch all bug and now have full test set. Then we could re-write the formatting code with Span to get more clear, fast and reliable code.