Allow override for 'run' and 'init' command in providers

[Diaphteiros]

What this PR does / why we need it:
Adds initCommand and runCommand fields to the spec of ServiceProvider, ClusterProvider, and PlatformService resources. They allow to override the default run and init commands. For backward compatibility, the field is optional and defaults to the previously expected values if not set.

Which issue(s) this PR fixes:
Loosely related to openmcp-project/backlog#210

Special notes for your reviewer:

Release note:

The `init` and `run` commands for providers can now be overwritten by using the respective fields in the spec of ServiceProvider`, `ClusterProvider`, and `PlatformService` resources.