Record template install version for flagging upgrades

[itowlson]

We currently record where templates originated from, but not any info that identifies their version (such as the inferred version tag they were installed from, or the Spin version that installed them).

If we did this, we would add something to spin new where it could say, "Hey, that template you're instantiating came from a different version of Spin than what you're using. Do you want to get the matching one?" Which would be annoying, though not as annoying as an ABI mismatch error.

That said, this still uses the Spin version as a proxy for compatibility. There's no value to the user in nagging them to rev their templates from 3.1 to 3.2 if there are no changes in the guest interfaces between those versions.