x/pkgsite: local setup - tracking issue

Today, users can run pkgsite locally without setting up a local database by running:

go run cmd/frontend/main.go -direct_proxy -proxy_url=<your proxy URL>

See flags in cmd/frontend/main.go, and doc/frontend.md for docs.

Doing so allows users to view the package documentation, overview, imports, and licenses tabs. Search and other tabs on the package page are not supported in direct proxy mode.

However, there are cases when a user might want to run pkgsite on their local machine, and be able to view a private repository that is not available via a proxy.

Tasks related to this topic:

• #40159: run locally to view documentation of a pending CL
• https://github.com/golang/go/issues/54479
• render the standard library for GOROOT
• link to github documentation when possible?
• #59542: add support for rendering vendor directories
• Display unexported symbols on request. (https://github.com/golang/go/issues/12092 https://github.com/golang/go/issues/59056#issuecomment-1518609724 )

Maybe:

• only render documentation for packages / units when they are accessed

This is an umbrella issue to discuss what features are needed for this to happen, so please comment on your use cases below. For discussions about hosting a private instance of pkgsite, including your own internal proxy, see #39827.