Add more attributes to local build context

[micbar]

Description

When using drone starlark locally, some of the context attributes which are available on drone server are missing

Added

• build.source_repo
• build.title

./drone starlark -h
NAME:
   drone starlark - generate .drone.yml from starlark

USAGE:
   drone starlark [command options] [path/to/.drone.star]

OPTIONS:
   --source value             Source file (default: ".drone.star")
   --target value             target file (default: ".drone.yml")
   --format                   Write output as formatted YAML
   --stdout                   Write output to stdout
   --repo.name value          repository name
   --repo.namespace value     repository namespace
   --repo.slug value          repository slug
   --build.event value        build event (default: "push")
   --build.branch value       build branch (default: "master")
   --build.source value       build source branch (default: "master")
   --build.source_repo value  repo slug of source repository
   --build.target value       build target branch (default: "master")
   --build.ref value          build ref (default: "refs/heads/master")
   --build.commit value       build commit sha
   --build.message value      build commit message
   --build.title value        build title

[micbar]

@tboerger @bradrydzewski

This addition makes it possible to convert complex starlark files into .yml

[tboerger]

@bradrydzewski WDYT?

[dschmidt]

@bradrydzewski ping?

[micbar]

@bradrydzewski @tboerger I rebased it.

Would be handy to get this merged.

[phil-davis]

@bradrydzewski please review and give your comments...

[phil-davis]

@bradrydzewski any chance for a release "soon"?

It would be nice to be able to use this change in a real release.

[phil-davis]

@bradrydzewski ping again - any chance for a release?

[phil-davis]

@bradrydzewski can you just take a few minutes to make a release with whatever code is in master?