checking version of plugins

[Two-Hearts]

Currently, the Notation: Sign action checks duplicate plugins by name. This is to reduce roundtrips and download time when multiple signings happen in a single workflow.
User might want to use different versions of plugins to produce different versions of signature for backward compatibility if there is a breaking change between those two versions.
Created this issue to track the above scenario.

Originally posted by @shizhMSFT in #31 (comment)