Emit single operation into multiple swaggers

[pshao25]

According to https://github.com/MicrosoftDocs/azure-docs-rest-apis/blob/main/reference.config.yml, firewallPolicy.json, network.json, azureWebCategory.json are in several places.

Take firewallPolicy.json as example, I checked msdoc, the operations for firewall are in both

https://learn.microsoft.com/en-us/rest/api/virtualnetwork/firewall-policies?view=rest-virtualnetwork-2025-05-01
https://learn.microsoft.com/en-us/rest/api/firewall/firewall-policies?view=rest-firewall-2025-05-01

We might need something like

@feature(VirtualNetwork)
@feature(Firewall)
op operation(): void;

And the operation is emitted into two corresponding swaggers.

[markcowl]

Looking at the source swagger

These operations exist in the firewallPolicy.json swagger

But they are not in virtualNetwork.json

So, however this was done, it was not by repeating operations in OpenAPI. Also, autorest is quite unlikely to be able to process one logical swagger that repeats the same operation.