Memoize validation of deprecated versions (#4273)
Memoize validation of deprecated versions (#4273)

### Problem

7% of the runtime for `./pants list` in our repo was being taken up in version validation (all for a relatively small set of deprecation versions used in pantsbuild/pants).

### Solution

Memoize validation of versions.
tdyas/pants,jsirois/pants,UnrememberMe/pants,wisechengyi/pants,wisechengyi/pants,benjyw/pants,lahosken/pants,baroquebobcat/pants,UnrememberMe/pants,pantsbuild/pants,tdyas/pants,landism/pants,pombredanne/pants,twitter/pants,UnrememberMe/pants,lahosken/pants,tdyas/pants,foursquare/pants,fkorotkov/pants,fkorotkov/pants,pantsbuild/pants,lahosken/pants,15Dkatz/pants,15Dkatz/pants,pantsbuild/pants,foursquare/pants,peiyuwang/pants,foursquare/pants,fkorotkov/pants,peiyuwang/pants,twitter/pants,peiyuwang/pants,UnrememberMe/pants,peiyuwang/pants,lahosken/pants,pombredanne/pants,fkorotkov/pants,wisechengyi/pants,baroquebobcat/pants,twitter/pants,UnrememberMe/pants,twitter/pants,foursquare/pants,15Dkatz/pants,twitter/pants,foursquare/pants,landism/pants,tdyas/pants,lahosken/pants,benjyw/pants,15Dkatz/pants,benjyw/pants,landism/pants,pantsbuild/pants,baroquebobcat/pants,pantsbuild/pants,pombredanne/pants,tdyas/pants,wisechengyi/pants,benjyw/pants,landism/pants,pantsbuild/pants,baroquebobcat/pants,tdyas/pants,fkorotkov/pants,landism/pants,baroquebobcat/pants,UnrememberMe/pants,wisechengyi/pants,fkorotkov/pants,tdyas/pants,jsirois/pants,wisechengyi/pants,baroquebobcat/pants,pombredanne/pants,landism/pants,15Dkatz/pants,UnrememberMe/pants,twitter/pants,lahosken/pants,foursquare/pants,landism/pants,foursquare/pants,peiyuwang/pants,15Dkatz/pants,tdyas/pants,pombredanne/pants,foursquare/pants,pombredanne/pants,foursquare/pants,baroquebobcat/pants,twitter/pants,lahosken/pants,benjyw/pants,twitter/pants,tdyas/pants,baroquebobcat/pants,UnrememberMe/pants,wisechengyi/pants,UnrememberMe/pants,peiyuwang/pants,pantsbuild/pants,benjyw/pants,baroquebobcat/pants,wisechengyi/pants,peiyuwang/pants,wisechengyi/pants,fkorotkov/pants,twitter/pants,landism/pants,pombredanne/pants,15Dkatz/pants,lahosken/pants,jsirois/pants,benjyw/pants,15Dkatz/pants,peiyuwang/pants,fkorotkov/pants