Added update command line argument -Version to fix Issue 1760

[casualblair]

Added update command line argument -Version

• Used to specify explicit version number of the package being updated
• Only works when -Id has been specified and contains exactly one package id

Added tests to cover both downgrade and upgrade options
Added description but needs localization

[dnfclas]

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[dnfclas]

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[yishaigalatzer]

@casualblair very exciting! Thanks for the PR.

CC @jainaashish @emgarten for reviewing and verifying.

FYI I don't expect this to get merged right away, we are working on releasing 3.4.4

[emgarten]

@casualblair very nice, thanks for fixing this!

[emgarten]

Merged with 214cfb0

This fixes NuGet/Home#1779