x/pkgsite: Support versions without "v" prefixes for module indexing

[criscola]

What did you expect to see?

I expect Semver tags without a v prefix to be indexed.

When Semver version tags do not contain a v prefix, indexing will not work

What did you see instead?

https://proxy.golang.org/github.com/bedag/kubernetes-dbaas/@v/1.0.0.info

returns this answer:

{"Version":"v0.0.0-20210824135149-99d66c68e799","Time":"2021-08-24T13:51:49Z"}

and does not index version 1.0.0.

I would like to have version 1.0.0 indexed. The reason for this is that git tags do not have to follow a precise standard, but if we look at what Semver says, basically v1.0.0 is not a valid version (but of course can be a valid git tag).

I think if we want to support Semver versions fully, then we should accept also that 1.0.0 is a valid tag, in my view. Of course v1.0.0 can also be accepted by the indexer because it's a common way of tagging release versions.

This behavior should be properly documented in the About.

Related

#47974

[seankhliao]

Duplicate of #32945