Go: improve UX of embed and resources

[Eric-Arellano]

To properly use embed, you must create a resources target and add it to the dependencies of your target. Can we make this more ergonomic? Like with #13784, we may want to:

1. Use tailor to create resources targets based on the embed patterns.
2. Add dependency inference.

Also, for now, a resource will only be added to the package if it has a corresponding embed directive. It's not enough to just add the resource target to the go_package. We think that is likely acceptable to avoid magic and make sure that if something builds with Pants, it still builds with standard Go tooling. But, we should probably detect this case and error.

[Eric-Arellano]

Dependency inference should be easier to do now thanks to @thejcannon 's #14049