feat: add boundary premium feature (#21589)

Source code changes:

- Added a wrapper for the boundary subcommand that checks feature
entitlement before executing the underlying command.
- Added a helper that returns the Boundary version using the
runtime/debug package, which reads this information from the go.mod
file.
- Added FeatureBoundary to the corresponding enum.
- Move boundary command from AGPL to enterprise.

`NOTE`: From now on, the Boundary version will be specified in go.mod
instead of being defined in AI modules.

docs/reference/cli/index.md

@@ -65,6 +65,7 @@ Coder — A tool for provisioning self-hosted development environments with Terr
 | [<code>support</code>](./support.md)                         | Commands for troubleshooting issues with a Coder deployment.                                                                 |
 | [<code>server</code>](./server.md)                           | Start a Coder server                                                                                                         |
 | [<code>provisioner</code>](./provisioner.md)                 | View and manage provisioner daemons and jobs                                                                                 |
+| [<code>boundary</code>](./boundary.md)                       | Network isolation tool for monitoring and restricting HTTP/HTTPS requests                                                    |
 | [<code>features</code>](./features.md)                       | List Enterprise features                                                                                                     |
 | [<code>licenses</code>](./licenses.md)                       | Add, delete, and list licenses                                                                                               |
 | [<code>groups</code>](./groups.md)                           | Manage groups                                                                                                                |