feat: use ports-clear plugn trigger to manage clearing the port map

This removes any access to the underlying implementation for port map clearing, which will make it easier to refactor the actual clearing.

docs/deployment/builders/dockerfiles.md

@@ -29,7 +29,7 @@ Dokku will only select the `dockerfile` builder if both the `herokuish` and `pac
 If an application was previously deployed via buildpacks, the following commands should be run before a Dockerfile deploy will succeed:
 
 ```shell
-dokku config:unset --no-restart node-js-app DOKKU_PROXY_PORT_MAP 
+dokku proxy:clear node-js-app
 ```
 
 ### Changing the `Dockerfile` location

docs/deployment/builders/herokuish-buildpacks.md

@@ -301,7 +301,7 @@ false
 If an application was previously deployed via Dockerfile, the following commands should be run before a buildpack deploy will succeed:
 
 ```shell
-dokku config:unset --no-restart node-js-app DOKKU_PROXY_PORT_MAP
+dokku ports:clear node-js-app
 ```
 
 ### Using a specific buildpack version

docs/development/plugin-triggers.md

@@ -1242,12 +1242,32 @@ nginx -t
 ```
 
 ### `ports-get`
+
 - Description: Returns a list of port mappings, newline delimited
 - Invoked by: Various networking plugins
 - Arguments `$APP`
+- Example:
+
 ```shell
 #!/usr/bin/env bash
+
 set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
+
+# TODO
+```
+
+### `ports-clear`
+
+- Description: Clears the ports for a given app without triggering further restarts or rebuilds
+- Invoked by: internally
+- Arguments: `$APP`
+- Example:
+
+```shell
+#!/usr/bin/env bash
+
+set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
+
 # TODO
 ```