Starlark support

Created by: olafurpg

We should improve search-based code intel support for the Starlark programming language https://github.com/bazelbuild/starlark

This would greatly improve the experience for Bazel users.

We already have a prototype that implements local navigation and cross-file navigation for load(...) statements. We should ship this.

• Publish new starlark code-intel extension
• Implement precise local navigation with Squirrel
• Implement precise navigation for basic load(...) statements
• Enable starlark code-intel extension everywhere
• Implement precise navigation for all load(...) statements