refactor: move code that fetches raw tcp ports for dockerfile deploys to ports plugin

docs/appendices/0.31.0-migration-guide.md

@@ -7,6 +7,7 @@
 - The `traefik` integration now mounts config to `/data` instead of the path `/acme.json`, fixing permissions issues under certain architectures. To take advantage of the new functionality, the traefik container should be stopped (via `dokku traefik:stop`) and then started (via `dokku traefik:start`).
 - Users no longer need to clear the `source-image` git property when transitioning from image-based deploys (`git:from-image` and `git:load-image`) to other deployment methods (git push, `git:from-archive`, `git:sync`).
 - For deploys via the `git:from-image` and `git:load-image` commands, the `CHECKS` file is now extracted from the configured `WORKDIR` property of the image. For all other deploys - git push, `git:from-archive`, `git:sync` - will have the `CHECKS` extracted directly from the source code. The filename in both cases is `CHECKS` and cannot be modified.
+- The `common#get_app_raw_tcp_ports()` function has been deprecated and will be removed in the next release. Users should avoid interacting with this function for dockerfile ports and instead use the `ports-get` plugin trigger for fetching ports for an app.
 
 ## Deprecations
 

docs/development/plugin-triggers.md

@@ -1256,6 +1256,23 @@ set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 # TODO
 ```
 
+### `ports-dockerfile-raw-tcp-ports`
+
+> Warning: This trigger is for internal use and will be removed in a future release. Do not use it in your codebase.
+
+- Description: Extracts raw tcp port numbers from DOCKERFILE_PORTS config variable
+- Invoked by: `internally triggered by proxy plugins`
+- Arguments: `$APP`
+- Example:
+
+```shell
+#!/usr/bin/env bash
+
+set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
+
+# TODO
+```
+
 ### `ports-get`
 
 - Description: Returns a list of port mappings, newline delimited