Initial Fabric support (#1607)

* Add Platform.Fabric to run in context of Fabric

* Use separate StyleConstants

We want to have more flexibility with Styles at runtime
but Constants depend on ConfigContext and therefore
get loaded very early at startup.

* Add Fabric specific styles and Fluent theme

documentDBFabric.less contains all styles for Fabric.
We use React.lazy to import them conditionally at
runtime preventing webpack from preprocessing
them into main.css.

* Restyle CommandBar for Fabric
with more roundness and native colors.

* Disable Notebooks when running in Fabric

* Disable Synapse and Scripts commands for Fabric

* Fix code formatting issues

* Fetch encrypted token from sessionStorage for fabric platform

* Fix Tabs style

* Dark refresh icons for Fabric

* Use new ResourceTree2 for Fabric

* Fluent tree should have a fixed width
otherwise the action buttons jump around on hover.

* Disable remaining Script actions in Fabric

* Revert accidentally committed change
which broke a test

* Fix cross-origin error second try

* Adjust @FabrixBoxMargin css

* Hide Database Scale node on Fabric

* Remove all Collection child nodes on Fabric

* Add a comment about why we need FabricPlatform.tsx

* Fix equality checks

* Fix more Colors for Fabric

* Switch resource tree to "medium" size

* Fix formatting again

* Fix formatting again

* Disable no-var-requires error on some intended var import.

* Increase memory limit for build

* Use standard Segoe UI font for Fabric

* Improve Tabs design for Fabric

* Fix active Tab style bug in Portal
introduced with 39a7765aef

---------

Co-authored-by: Laurent Nguyen <laurent.nguyen@microsoft.com>

less/Common/Constants.less

@@ -10,6 +10,7 @@
 @DataExplorerFont: wf_segoe-ui_normal, "Segoe UI", "Segoe WP", Tahoma, Arial, sans-serif;
 @SemiboldFont: "Segoe UI Semibold", "Segoe UI", "Segoe WP", Tahoma, Arial, sans-serif;
 @GrayScale: "grayscale()";
+@NoColor: "brightness(0) saturate(100%)";
 
 @xSmallFontSize: 4px;
 @smallFontSize: 8px;
@@ -147,14 +148,41 @@
 // CommandBar
 @CommandBarButtonHeight: 40px;
 
+/**********************************************************************************
+                              Portal Consts
+/**********************************************************************************/
+
+@PortalAccentMediumHigh: #0058ad;
+@PortalAccentMedium: #004e87;
+@PortalAccentLight: #eef7ff;
+@PortalAccentAccentExtra: #ddf0ff;
+
+/**********************************************************************************
+                              Fabric Consts
+/**********************************************************************************/
+
+@FabricFont: "Segoe UI", "Segoe UI Web (West European)", "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif;
+
+@FabricBoxBorderRadius: 8px;
+@FabricBoxBorderShadow: 0 0 2px rgba(0, 0, 0, 0.12), 0 2px 4px rgba(0, 0, 0, 0.14);
+@FabricBoxMargin: 4px 3px 4px 3px;
+
+@FabricAccentMediumHigh: #0c695a;
+@FabricAccentMedium: #117865;
+@FabricAccentLight: #f5f5f5;
+@FabricAccentExtra: #ebebeb;
+
+@FabricButtonBorderRadius: 4px;
+
+
 /**********************************************************************************
                               Common Flex Property
 /**********************************************************************************/
 
 .flex-display(@display: flex) {
-  display: ~"-webkit-@{display}";
-  display: ~"-ms-@{display}box"; // IE10 uses -ms-flexbox
-  display: ~"-ms-@{display}"; // IE11
+  display:~"-webkit-@{display}";
+  display:~"-ms-@{display}box"; // IE10 uses -ms-flexbox
+  display:~"-ms-@{display}"; // IE11
   display: @display;
 }
 
@@ -168,13 +196,15 @@
                                  High contrast mode active
 **************************************************************************************/
 
-@media all and (-ms-high-contrast: none), (-ms-high-contrast: active) {
+@media all and (-ms-high-contrast: none),
+(-ms-high-contrast: active) {
+
   .selectedRadio,
   .selectedRadio:hover,
   .selectedRadio:active,
   .selectedRadio.dirty,
-  .tab [type="radio"]:checked ~ label,
-  .tab [type="radio"]:checked ~ label:hover {
+  .tab [type="radio"]:checked~label,
+  .tab [type="radio"]:checked~label:hover {
     -ms-high-contrast-adjust: none;
     -webkit-text-fill-color: HighlightText;
     color: HighlightText;
@@ -183,6 +213,7 @@
   }
 
   .queryMetricsSummaryTuple {
+
     th,
     td {
       &:nth-child(2) {
@@ -302,4 +333,4 @@
   width: 0;
   height: 0;
   border-color: @InfoPointerColor transparent;
-}
+}