Pull request: beta client squashed

Merge in DNS/adguard-home from beta-client-2 to master

Squashed commit of the following:

commit b2640cc49a6c5484d730b534dcf5a8013d7fa478
Merge: 659def862 aef4659e9
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Dec 29 19:23:09 2020 +0300

    Merge branch 'master' into beta-client-2

commit 659def8626467949c35b7a6a0c99ffafb07b4385
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Dec 29 17:25:14 2020 +0300

    all: upgrade github actions node version

commit b4b8cf8dd75672e9155da5d111ac66e8f5ba1535
Author: Vladislav Abdulmyanov <v.abdulmyanov@adguard.com>
Date:   Tue Dec 29 16:57:14 2020 +0300

    all: beta client squashed

client2/postcss.config.js

@@ -0,0 +1,17 @@
+module.exports = {
+    plugins: [
+        ['postcss-import', {}],
+        ['postcss-nested', {}],
+        ['postcss-custom-media', {}],
+        ['postcss-variables', {}],
+        ['postcss-calc', {}],
+        ['postcss-mixins', {}],
+        ['postcss-preset-env', { stage: 3, features: { 'nesting-rules': true } }],
+        ['postcss-reporter', { clearMessages: true }],
+        ['postcss-inline-svg', {
+            paths: ['frontend/icons', 'vendor/adguard/utils-bundle/src/Resources/frontend/icons'],
+            svgo: { plugins: [{ cleanupAttrs: true }] } 
+        }],
+        ['autoprefixer'],
+    ]
+};