[Suggestion] Support flexible paths for secrets

[Peter2121]

Hello, thanks a lot for this plugin, many people are waiting for it (me too).
There is one problem of the plugin's design though.
If one start 'from scratch' - everything is fine, the secrets will be stored/retrieved at the paths you want:

    /device/{id}/{slug} for Devices
    /vm/{id}/{slug} for Virtual Machines
    /service/{id}/{slug} for Services

   "secret_path_prefix": "/netbox",

But what about the existing Vault installation, where many secrets are ALREADY stored, at some paths?
I think that this plugin should have a flexibility to configure the path for every secret.
It means that the user should be able not only add a secret at the 'standard' path, but he should be able to link an existing secret at a custom path to a device/VM/service too.
It does not seem to be a really complex modification, but it should be done at the beginning of the development of the plugin, because IMHO it will be more difficult later.