Support for label/name prefix and suffix

[gessnerfl]

Story

I want to be able to define a prefix and a suffix which should be added to each name or label
So that my resources get a consistent naming within e.g. a particular environment

Technical Details

With #19 the option append the string ' (TF managed)' was added to the provider. This helps to identify that a resource is managed by terraform but is already very opinionated and restricted.

With this story the options for a default prefix and suffix for resource names/labels should be provided.

• By default there should be no prefix
• By default the suffix should be set to ' (TF managed)'

The configuration option of #19 becomes obsolete with this change and can be deleted.
The resources should be migrated properly.