Add new incus_network_peer resource

[Unitiser]

Hello,

This is the PR for #123.

[stgraber]

@Unitiser any chance you can update your PR based on the comments above?
Also, we just merged #173 which comes with a few disabled tests that are waiting on this PR, it'd be great to add a commit which enables them.

[Unitiser]

Hello, I apologize for the delay.

I made the fix you requested, hope this helps!

[maveonair]

@Unitiser Please merge origin main or rebase from origin main to get the latest fixes required for CI/CD to work.

[maveonair]

This pull request must be above the latest main branch in order to receive the required corrections for CI/CD

[Unitiser]

@maveonair I resync'd the branch using the Github UI. Let me know if that's enough.

[stgraber]

 === RUN   TestAccNetworkIntegration_attach
    resource_network_integration_test.go:99: Step 1/1 error: Error running pre-apply plan: exit status 1
        
        Error: Missing required argument
        
          on terraform_plugin_test.tf line 46, in resource "incus_network_peer" "test":
          46: resource "incus_network_peer" "test" {
        
        The argument "target_network" is required, but no definition was found.
--- FAIL: TestAccNetworkIntegration_attach (0.26s)