fix: Standardize errors to track with Commonalities

[caubut-charter]

Problem description
Breaking down #19 as being too large for a single PR. This PR focuses just on error messages.

Expected behavior
These need to be reviewed as the correct error type:

• NetworkNotRemovable400 - For devices that MUST have a single network (e.g. consumer grade APs).
• DefaultDeviceNotSupported403 - For situations where the default device cannot be inferred.
• 501 - A large portion of the API doesn't need to be implemented for the simplest use case. The added scope for B2B2* scenarios added many new endpoints and added additional functionality to existing endpoints.
• Fix any examples and anchors to be appropriate for any given endpoint.

Alternative solution
N/A. Requirement.

Additional context

Error codes also in this pass: https://github.com/camaraproject/Commonalities/blob/main/documentation/API-design-guidelines.md#61-standardized-use-of-camara-error-responses

For this you can copy/paste from https://github.com/camaraproject/Commonalities/blob/main/artifacts/CAMARA_common.yaml

In addition you might want to consider which operation are "allowed" to return a 501 (NOT_IMPLEMENTED). There was a TSC discussion about camaraproject/Commonalities#246 with the result that "Mandatory endpoints must not have 501 defined as a valid response". Currently you have defined 501 as a potential response for all operations, but I don't think you want to indicate that the implementation of all these endpoints is "optional".