Integrate starlib and bazel-skylib

[jordemort]

Extend the API to allow extra parameters to be passed to the Starlark() constructor that specify additional Starlark libraries to make available in the interpreter.

starlib

https://github.com/qri-io/starlib

These look to be written in Go and will need to be compiled into the extension.

bazel-skylib

https://github.com/bazelbuild/bazel-skylib/tree/main/lib

Some of this is bazel-specific and won't be useful, but the path manipulation and type introspection stuff is ❇️

This stuff is in Starlark, so we probably just want to vendor the files we want and exec them upon request.

[seperman]

Hello, any updates on integrating Starlib? Thanks.

[colindean]

My particular use case— testing Vela templates written in Starlark— pairs well with sprig, or at least a library with the same implementations, since that's what's used on the Go-template version of Vela's templates. Eventually, I'd want to make available to my testing framework functionality matching precisely what's available in Vela for Go-templates… Vela's Starlark doesn't actually include sprig as of v0.27.4.

It'd be neat if we could dynamically load these support libraries somehow. Loading stuff written in Starlark should be pretty easy, but doing so for Go-written support libraries might be harder.

[colindean]

Starlib appears to be unmaintained: qri-io/starlib#179