Merge 3.9 RC5 fixes into master (#6459)

* UI fixes for 3.9 (#6400)

* UI fixes for header icon alignment

* PLT-6569 - Fixing pin icon in header

* PLT-6505 - Updating z-index for emoji picker

* Updating z-index for overlaying sidebar

* PLT-6134 - Fix for emoji picker on comments

* Reverting emoji picker fix

* Fixing alignment for header icons

* Removing channel title changes

* Don't show mention badge for active channel (#6411)

* PLT-6583 - Fixing RHS compact view (#6413)

webapp/sass/layout/_navigation.scss

@@ -41,14 +41,6 @@
             width: 43px;
             z-index: 5;
 
-            > span {
-                > svg {
-                    position: relative;
-                    top: 13px;
-                    vertical-align: top;
-                }
-            }
-
             .icon-bar {
                 background: $white;
                 width: 21px;
@@ -57,8 +49,7 @@
             .icon-search {
                 font-size: 17px;
                 position: relative;
-                top: 11px;
-                vertical-align: top;
+                top: -2px;
             }
 
             .icon--white {