Multitenancy: do not require main wallet api-key when invoking subwallet functions

[esune]

When running ACA-Py in multitenancy mode, requests directed to an API controlling a subwallet function still require the main wallet x-api-key to be provided in the request headers for the request to succeed.

While there are ways to "mask" this from a user by proxying the request, it would be nice if the main wallet x-api-key header was only required for operations related to tenant provisioning and management, and not for requests directed to a subwallet.