Sampath accessibility sev 2 2 (#1404)

* autoscale and manual radiobuutton fixes

* alt text attribute for images

* Revert "alt text attribute for images"

This reverts commit 5a660551c6.

* alt text for decorative images

* sev2 accessibilitydefects in data explorer

* Revert "sev2 accessibilitydefects in data explorer"

This reverts commit b84d5b572c.

* Sev2 accessibilitydefects

* Revert "Sev2 accessibilitydefects"

This reverts commit a4e60f106c.

* accessibilitydefects-data explorer

* Accessibility sev-2 defects-2

* corrections for 2278347,2278096 and fix for 2264174

* color for placeholder changed to 767474, margin is set to accommodate height between treeheader elements

* padding added for databaseheader, removed margin and restored padding to treenodeheader

less/documentDB.less

@@ -2576,6 +2576,10 @@ a:link {
 .querydropdown.placeholderVisible {
   font-style: italic;
 }
+.querydropdown.placeholderVisible::placeholder { /* Chrome, Firefox, Opera, Safari 10.1+ */
+  color: #767474;
+  opacity: 1; 
+}
 
 .querydropdown:hover {
   background-color: @AccentLow;
@@ -3087,3 +3091,4 @@ a:link {
   background: white;
   height: 100%;
 }
+

less/resourceTree.less

@@ -5,6 +5,7 @@
   overflow: auto;
 
   .databaseHeader {
+    padding: 1px;
     font-size: 14px;
   }