Add network egress resource (#357)

This change adds a new import resource which enables exposing Netbird
resources as Kubernetes services. This remove the need to add sidecars
to every pod.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Added a new `NetworkEgress` custom resource (`netbird.io/v1alpha1`)
with CRD, schema validation, and status/conditions.
* Extended controller functionality to create egress services and
translate egress rules into import `EndpointSlice` resources; egress
pods now include a kube-egress-forwarder sidecar.
* **Bug Fixes**
* Added missing deep-copy and declarative apply support for the new
`NetworkEgress` API types.
* **Documentation**
* Updated README/API reference and added example manifests for
`NetworkEgress` (including IP/FQDN target usage).
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Signed-off-by: Philip Laine <philip.laine@gmail.com>

pkg/applyconfigurations/api/v1alpha1/networkegressspec.go

@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Code generated by controller-gen. DO NOT EDIT.
+
+package v1alpha1
+
+// NetworkEgressSpecApplyConfiguration represents a declarative configuration of the NetworkEgressSpec type for use
+// with apply.
+//
+// NetworkEgressSpec defines the desired state of NetworkEgress.
+type NetworkEgressSpecApplyConfiguration struct {
+	// NetworkRouterRef is a reference to the network and router where the resource will be created.
+	NetworkRouterRef *CrossNamespaceReferenceApplyConfiguration `json:"networkRouterRef,omitempty"`
+	// Target for egress traffic.
+	Target *NetworkEgressTargetApplyConfiguration `json:"target,omitempty"`
+	// Ports to the resource to route.
+	Ports []NetworkEgressPortApplyConfiguration `json:"ports,omitempty"`
+}
+
+// NetworkEgressSpecApplyConfiguration constructs a declarative configuration of the NetworkEgressSpec type for use with
+// apply.
+func NetworkEgressSpec() *NetworkEgressSpecApplyConfiguration {
+	return &NetworkEgressSpecApplyConfiguration{}
+}
+
+// WithNetworkRouterRef sets the NetworkRouterRef field in the declarative configuration to the given value
+// and returns the receiver, so that objects can be built by chaining "With" function invocations.
+// If called multiple times, the NetworkRouterRef field is set to the value of the last call.
+func (b *NetworkEgressSpecApplyConfiguration) WithNetworkRouterRef(value *CrossNamespaceReferenceApplyConfiguration) *NetworkEgressSpecApplyConfiguration {
+	b.NetworkRouterRef = value
+	return b
+}
+
+// WithTarget sets the Target field in the declarative configuration to the given value
+// and returns the receiver, so that objects can be built by chaining "With" function invocations.
+// If called multiple times, the Target field is set to the value of the last call.
+func (b *NetworkEgressSpecApplyConfiguration) WithTarget(value *NetworkEgressTargetApplyConfiguration) *NetworkEgressSpecApplyConfiguration {
+	b.Target = value
+	return b
+}
+
+// WithPorts adds the given value to the Ports field in the declarative configuration
+// and returns the receiver, so that objects can be build by chaining "With" function invocations.
+// If called multiple times, values provided by each call will be appended to the Ports field.
+func (b *NetworkEgressSpecApplyConfiguration) WithPorts(values ...*NetworkEgressPortApplyConfiguration) *NetworkEgressSpecApplyConfiguration {
+	for i := range values {
+		if values[i] == nil {
+			panic("nil value passed to WithPorts")
+		}
+		b.Ports = append(b.Ports, *values[i])
+	}
+	return b
+}