Dokku ships with default charts and customizes their helm values. In certain cases, it may be useful to further customize those values to better support specific installations. With this change, it is now possible to set custom values by providing the key in the format `chart.$CHART_NAME.$PROPERTY`. For instance, to increase timeouts for the keda http addon:

```shell
dokku scheduler-k3s:set --global chart.keda-add-ons-http.interceptor.tcpConnectTimeout 120s
dokku scheduler-k3s:set --global chart.keda-add-ons-http.interceptor.keepAlive 120s
dokku scheduler-k3s:set --global chart.keda-add-ons-http.interceptor.responseHeaderTimeout 120s
dokku scheduler-k3s:set --global chart.keda-add-ons-http.interceptor.idleConnTimeout 120s
dokku scheduler-k3s:set --global chart.keda-add-ons-http.interceptor.tlsHandshakeTimeout 120s
dokku scheduler-k3s:set --global chart.keda-add-ons-http.interceptor.expectContinueTimeout 120s
```

To reset a value to its default, simply set the value to an empty string.

```shell
dokku scheduler-k3s:set --global chart.keda-add-ons-http.interceptor.tcpConnectTimeout
```

Once the values are set, users will need to then run `scheduler-k3s:ensure-charts` with either the `--force` flag or specify the `--chart` flag with a list of charts to force apply.

```shell
dokku scheduler-k3s:ensure-charts --force

dokku scheduler-k3s:ensure-charts --chart keda-add-ons-http
```

Note that the existing dokku-provided values cannot be removed, but can be overridden.