Add ProxyPolicy enum

src/enums.js

@@ -13,6 +13,13 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */
+const ProxyPolicy =  {
+  ADAPTIVE: 'adaptive',
+  ALWAYS: 'always',
+  NEVER: 'nver',
+}
+Object.freeze(ProxyPolicy)
+
 const Fetcher =  {
   HTTP: 'http',
   DNS: 'dns',
@@ -52,6 +59,7 @@ const ClaimRelation =  {
 }
 Object.freeze(ClaimRelation)
 
+exports.ProxyPolicy = ProxyPolicy
 exports.Fetcher = Fetcher
 exports.ProofAccess = ProofAccess
 exports.ProofFormat = ProofFormat