Fixes an oversight in https://github.com/coder/coder/pull/17032
The FE has logic to replace the string `$SESSION_TOKEN` with a
newly-minted session token.
This adds corresponding logic to the `coder open app` command.
Fixes https://github.com/coder/coder/issues/17009
Adds a CLI command `coder open app <workspace> <app-slug>` that allows
opening arbitrary `coder_apps` via the CLI.
Users can optionally specify a region for workspace
applications.