UW-500 - Allow forced conversion between formats

[WeirAE]

Description
User story: Can you use config realize to translate a config file from one format to another? E.g., I wanted to take an nml file and convert it to .yaml. Could I do that via uw config realize -i foo.nml --input-format nml -o foo.yaml --output-format yaml?

Requirements
YAML should always be accepted as input or output format. Documentation and tests must be updated appropriately

Acceptance Criteria (Definition of Done)
ability to convert supported formats to yaml format is restored
--force flag for overriding the check that allows YAML to convert to other file formats
documentation updated
tests updated

Additional context
Allowing YAML as always accepted supplemental file will be covered in UW-504

[WeirAE]

Marked as 'refactor' as this behavior was reasonably expected rather than necessarily 'new'

[WeirAE]

Initial testing shows that YAML is already accepted, tested and documented as universally allowed input, so perhaps --force is not needed, only improved documentation

[WeirAE]

After further re-checking requirements and testing, YAML as output has some issues in creating a valid YAML from sh/ini or nml dicts. This may again require --force to allow this behavior.
Updating the AC to read:
--force flag for overriding the check to allow all file formats to convert to YAML

[WeirAE]

Further discussion in group: we will allow YAML as output always, for much the same reason it is a valid input. However, this will be exclusive to YAML explicitly.

[WeirAE]

Completed by #414