Pull request: client: add reset leases btn

Updates #1691.

Squashed commit of the following:

commit 2c48fb956aba28eae47071c9f7f4d579dde12955
Merge: 38f5191b 7547d3a4
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Jun 17 14:28:23 2021 +0300

    Merge branch 'master' into 1691-dhcp-reset-form

commit 38f5191bcd62eb53e4663fccdfc2a60247881931
Author: Ildar Kamalov <ik@adguard.com>
Date:   Thu Jun 17 13:14:59 2021 +0300

    client: handle dhcp leases reset

commit a97df17028ca640fd32b4d9762aa54fb381df7e5
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Wed Jun 16 17:12:10 2021 +0300

    client: add reset leases btn

client/src/reducers/dhcp.js

@@ -118,6 +118,11 @@ const dhcp = handleActions(
             v6: {},
             interface_name: '',
         }),
+        [actions.resetDhcpLeasesSuccess]: (state) => ({
+            ...state,
+            leases: [],
+            staticLeases: [],
+        }),
 
         [actions.toggleLeaseModal]: (state) => {
             const newState = {