[reloader] Add a PluginDefinition for stakater/reloader

[IvoGoman]

Priority

(Medium) I'm annoyed but I'll live

Is your feature request related to a problem?

The reloader by stakater is quite a useful tool to rotatate credentials or to make sure that pods are restarted if referenced ConfigMaps/Secrets change.

It also brings its own helm chart which can be used for the Plugin

Additional context.

The helm chart for the reloader can be found here and it is uploaded to ghcr

As part of this a PluginDefinition with sane defaults and some basic configurations as PluginOptions should be created.
Also a custom manager should be added to the renovate configuration to receive automatic updates on helm chart changes.

Reference Issues

No response