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/iptarget.go

@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Code generated by controller-gen. DO NOT EDIT.
+
+package v1alpha1
+
+// IPTargetApplyConfiguration represents a declarative configuration of the IPTarget type for use
+// with apply.
+//
+// IPTarget is a single IPv4 or IPv6 address.
+type IPTargetApplyConfiguration struct {
+	// Address is a single IP address.
+	Address *string `json:"address,omitempty"`
+}
+
+// IPTargetApplyConfiguration constructs a declarative configuration of the IPTarget type for use with
+// apply.
+func IPTarget() *IPTargetApplyConfiguration {
+	return &IPTargetApplyConfiguration{}
+}
+
+// WithAddress sets the Address 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 Address field is set to the value of the last call.
+func (b *IPTargetApplyConfiguration) WithAddress(value string) *IPTargetApplyConfiguration {
+	b.Address = &value
+	return b
+}