`visibility` attr should allow more concise syntax

### Context
Currently, when specifying visibility for a target, you need to use an oddly verbose syntax ([spec](https://bazel.build/concepts/visibility#visibility-specifications)):

> - `//foo/bar:__pkg__`: Grants access to `//foo/bar` (but not its subpackages).
> - `//foo/bar:__subpackages__`: Grants access `//foo/bar` and all of its direct and indirect subpackages.

Here at Stripe, most engineers don't remember this syntax, and struggle to configure visibility. This often results in users simply avoiding visibility, leading to surprising and illegal dependencies being checked into the source code, only to be discovered later.

### Proposal

It would be more ergonomic to allow shorter patterns, consistent with target label patterns:

> - `//foo/bar:all`: Grants access to `//foo/bar` (but not its subpackages).
> - `//foo/bar/...`: Grants access `//foo/bar` and all of its direct and indirect subpackages.

Start by reading the visibility specifications linked in the issue and compare them with the target label patterns described in the proposal. Done means visibility accepts `//foo/bar:all` and `//foo/bar/...` with the stated package-only and recursive-subpackage semantics.

Written by the indexing model from the issue text.