[misc] Move shared components to shared directory (#4286)

Moved the following directories:

```
  - management/client → shared/management/client
  - management/domain → shared/management/domain
  - management/proto → shared/management/proto
  - signal/client → shared/signal/client
  - signal/proto → shared/signal/proto
  - relay/client → shared/relay/client
  - relay/auth → shared/relay/auth
```

and adjusted import paths

shared/management/client/rest/policies.go

@@ -0,0 +1,96 @@
+package rest
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+
+	"github.com/netbirdio/netbird/management/server/http/api"
+)
+
+// PoliciesAPI APIs for Policies, do not use directly
+type PoliciesAPI struct {
+	c *Client
+}
+
+// List list all policies
+// See more: https://docs.netbird.io/api/resources/policies#list-all-policies
+func (a *PoliciesAPI) List(ctx context.Context) ([]api.Policy, error) {
+	path := "/api/policies"
+
+	resp, err := a.c.NewRequest(ctx, "GET", path, nil, nil)
+	if err != nil {
+		return nil, err
+	}
+	if resp.Body != nil {
+		defer resp.Body.Close()
+	}
+	ret, err := parseResponse[[]api.Policy](resp)
+	return ret, err
+}
+
+// Get get policy info
+// See more: https://docs.netbird.io/api/resources/policies#retrieve-a-policy
+func (a *PoliciesAPI) Get(ctx context.Context, policyID string) (*api.Policy, error) {
+	resp, err := a.c.NewRequest(ctx, "GET", "/api/policies/"+policyID, nil, nil)
+	if err != nil {
+		return nil, err
+	}
+	if resp.Body != nil {
+		defer resp.Body.Close()
+	}
+	ret, err := parseResponse[api.Policy](resp)
+	return &ret, err
+}
+
+// Create create new policy
+// See more: https://docs.netbird.io/api/resources/policies#create-a-policy
+func (a *PoliciesAPI) Create(ctx context.Context, request api.PostApiPoliciesJSONRequestBody) (*api.Policy, error) {
+	requestBytes, err := json.Marshal(request)
+	if err != nil {
+		return nil, err
+	}
+	resp, err := a.c.NewRequest(ctx, "POST", "/api/policies", bytes.NewReader(requestBytes), nil)
+	if err != nil {
+		return nil, err
+	}
+	if resp.Body != nil {
+		defer resp.Body.Close()
+	}
+	ret, err := parseResponse[api.Policy](resp)
+	return &ret, err
+}
+
+// Update update policy info
+// See more: https://docs.netbird.io/api/resources/policies#update-a-policy
+func (a *PoliciesAPI) Update(ctx context.Context, policyID string, request api.PutApiPoliciesPolicyIdJSONRequestBody) (*api.Policy, error) {
+	path := "/api/policies/" + policyID
+
+	requestBytes, err := json.Marshal(request)
+	if err != nil {
+		return nil, err
+	}
+	resp, err := a.c.NewRequest(ctx, "PUT", path, bytes.NewReader(requestBytes), nil)
+	if err != nil {
+		return nil, err
+	}
+	if resp.Body != nil {
+		defer resp.Body.Close()
+	}
+	ret, err := parseResponse[api.Policy](resp)
+	return &ret, err
+}
+
+// Delete delete policy
+// See more: https://docs.netbird.io/api/resources/policies#delete-a-policy
+func (a *PoliciesAPI) Delete(ctx context.Context, policyID string) error {
+	resp, err := a.c.NewRequest(ctx, "DELETE", "/api/policies/"+policyID, nil, nil)
+	if err != nil {
+		return err
+	}
+	if resp.Body != nil {
+		defer resp.Body.Close()
+	}
+
+	return nil
+}