Merge: + client: handle client block and unblock from the top clients table

Closes #896

Squashed commit of the following:

commit 776de2ae0a62823b8968cff79a9fa7ba350d7f1c
Author: Ildar Kamalov <i.kamalov@adguard.com>
Date:   Thu Jan 30 11:13:41 2020 +0300

    - client: fix normalizeTextarea and blocking button

commit 399e6bc3893093632b09247eaf6493521a668c84
Author: Ildar Kamalov <i.kamalov@adguard.com>
Date:   Wed Jan 29 17:19:50 2020 +0300

    + client: handle client block and unblock from the top clients table

client/src/helpers/constants.js

@@ -456,3 +456,8 @@ export const DETAILED_DATE_FORMAT_OPTIONS = {
 };
 
 export const CUSTOM_FILTERING_RULES_ID = 0;
+
+export const ACTION = {
+    block: 'block',
+    unblock: 'unblock',
+};