PLT-3782 Do not move the "@" sign and flag icon to the left of search bar when opening the right hand sidebar (#4850)

* do not move the mention & flag button to the left of the search box when in search mode

* fixed the margin & padding issues of the search box

* fixed the member icon positioning issue and the expanded sidebar toggle issue

* fixed remaining bugs when sidebar is in expanded mode

* changed propTypes from func to bool

webapp/sass/components/_search.scss

@@ -74,7 +74,10 @@
     }
 
     .sidebar--right & {
-        width: 100%;
+        width: 300px;
+        float: left;
+        margin-left: 17px;
+        margin-right: 9px;
     }
 
     .search-bar {

webapp/sass/components/_webrtc.scss

@@ -347,4 +347,8 @@
     #videos.small {
         position: relative;
     }
+
+    .search__form {
+        width: calc(100% - 92px);
+    }
 }