Configuration of fine-tuning scripts by YAML file

[mseeger]

Is your feature request related to a problem? Please describe.
Currently, all configurations must be provided via CL or hard-coded.

Describe the solution you'd like
I'd like to have a config option by a YAML file:

• Should also allow specification of CL arguments. Priority would be: CL arg -> config.yaml -> defaults in code
• Would solve Support setting different cache lengths for each layer via the CLI #9, maybe also Support different cache types for each layer. Gradient computations when all or some caches are of type DenseKVCache #10
• Important sub-task: Support (1) different cache lengths per layer and (2) different cache types per layer. The latter would require some extra refactoring, since right now, cache types must be the same

[mseeger]

In case anybody wants to work on this one: Please send me a plan how this should look like first. Let us discuss before you send me a long PR.

Also, an integration with something existing is much more welcome than a lot of new code.