feat: implement proxy-clear-config

This will allow us to kill stale proxy configuration within apps, which is critical during application renames.

- redirect rmdir output to dev-null
- trigger a proxy-clear-config (new trigger) when renaming an application
  - The configuration will be rebuilt during the later `ps_rebuild`

Closes #3231

docs/development/plugin-triggers.md

@@ -373,6 +373,21 @@ set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 # TODO
 ```
 
+### `network-clear-config`
+
+- Description: Clears network configuration
+- Invoked by: `internally triggered by proxy-clear-config within proxy implementations`
+- Arguments: `$APP`
+- Example:
+
+```shell
+#!/usr/bin/env bash
+
+set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
+
+# TODO
+```
+
 ### `network-compute-ports`
 
 - Description: Computes the ports for a given app container
@@ -1040,6 +1055,21 @@ set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 # TODO
 ```
 
+### `proxy-clear-config`
+
+- Description: Clears the proxy implementation configuration for a given app
+- Invoked by: `internally triggered by apps:rename`
+- Arguments: `$APP`
+- Example:
+
+```shell
+#!/usr/bin/env bash
+
+set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
+
+# TODO
+```
+
 ### `proxy-enable`
 
 - Description: Enables the configured proxy implementation for an app