[Accesses API] Improve error handling when access is requested at incorrect time

[rkandoi]

Add error codes for cases when accesses is requested when not allowed (for example when network is in TERMINATED state).

[tlohmar]

Just wondering, whether one of the newly inserted 422 error codes, specifically the "422_SERVICE_NOT_APPLICABLE" (Service not applicable for the provided identifier) error code can be reused here. The Service corresponds to the Access API usage and the provided identifier is the identifier of the Network, which is in a wrong state.

[tlohmar]

FY, I triggered a discussion in Commonalities: camaraproject/Commonalities#521

[tlohmar]

Conclusion from Commonalities: Status Code 422 should only be used for Device Identifier related issues.
Therefore, the group agreed to use 409 Status Code instead.