**Summary of Changes**

This pull request is a significant refactoring of how ComputeNetworkRef, a reference to a ComputeNetwork resource, is handled within the Config Connector codebase. The core change
involves moving the ComputeNetworkRef type definition from the generic apis/refs/v1beta1 package to the more specific apis/compute/v1beta1 package.

The purpose of this refactoring is to improve code organization and maintainability by placing the reference type alongside the resource it refers to. As part of this change, the
logic for normalizing the external reference format has been improved and centralized in the new network_reference.go file. This new implementation, NormalizedExternal, handles
resolving the reference from either an external field or a name and namespace pair, and it also includes logic to handle different URL formats for backward compatibility.

The PR touches a large number of files because it updates all the resources that use ComputeNetworkRef to point to the new location. This includes updating the CRD definitions, the Go
type definitions for various resources, and the direct controller logic that resolves these references.

**Implementation Analysis**

The implementation appears to be a sound and well-executed refactoring. The new ComputeNetworkRef implementation in apis/compute/v1beta1/network_reference.go is more robust than the
previous one. It correctly handles resolving the reference from either the external field or the name/namespace fields, and it also includes logic to handle different URL formats from
GCP, which improves backward compatibility.

The introduction of FixStaleExternalFormat in apis/common/utils.go is a good addition to handle various URL prefixes that might be present in the external field. The new
NetworkIdentity struct provides a clean way to parse and represent the components of a ComputeNetwork's external identifier.

The changes are spread across many files, but they are all related to updating the import path of ComputeNetworkRef. The logic changes are concentrated in the new
apis/compute/v1beta1/network_reference.go and apis/compute/v1beta1/network_identity.go files, and in the direct controllers that now use the new NormalizedExternal method. The changes
in the direct controllers are minimal and consistent, simply replacing the old normalization logic with a call to the new method.

**Testing Gaps**

The author states in a comment that there are no untested ComputeNetwork references in direct resources and that the golden logs have not changed after the refactoring. This suggests
that the existing test suite provides good coverage for this change. However, given the scale of the refactoring, it would be beneficial to have explicit unit tests for the new
NormalizedExternal function to cover various scenarios, such as:

 * Resolving from external with a full URL.
 * Resolving from external with a partial URL.
 * Resolving from name and namespace.
 * Handling cases where the referenced ComputeNetwork does not exist.
 * Handling various stale external formats in FixStaleExternalFormat.

While the existing E2E tests seem to cover the functionality, adding these unit tests would provide more targeted and faster feedback for any future changes to this logic.

**Backward Compatibility**

This PR is a breaking change for any external users who might be importing the refs.ComputeNetworkRef type directly. However, since this is an internal refactoring and all internal
call sites have been updated, it is an acceptable breaking change within the pkg/ directory.

For users of the CRDs, this change is backward compatible. The CRD definitions have been updated to reflect the new structure, but the user-facing API remains the same. The logic in
NormalizedExternal is designed to be backward compatible with the old URL formats, so existing resources should continue to work without any issues.

**Performance & Scalability**

The changes are in the critical path of the direct controllers' reconciliation logic. However, the new implementation for resolving references is not expected to have any negative
performance impact. The logic is efficient and involves simple string manipulations and a single Kubernetes API call to fetch the referenced ComputeNetwork resource when needed. There
are no new scalability bottlenecks introduced.

**Security Considerations**

This refactoring does not introduce any new security vulnerabilities. The changes are focused on code organization and improving the reference resolution logic. There are no changes
to how credentials or sensitive information are handled.

**Maintainability & Code Organization**

This PR significantly improves the maintainability and code organization of the project. Moving the ComputeNetworkRef to the apis/compute/v1beta1 package makes the codebase more
modular and easier to understand. Centralizing the reference resolution logic in the NormalizedExternal function reduces code duplication and makes it easier to maintain and update in
the future. The introduction of NetworkIdentity and FixStaleExternalFormat also contributes to cleaner and more robust code.