fix(navdrawer): active iem background contrast with the text color

Author: MPopov

projects/igniteui-angular/src/lib/core/styles/themes/schemas/dark/_navdrawer.scss

@@ -83,7 +83,7 @@ $_dark-indigo-navdrawer: extend(
 
         item-active-background: (
             igx-contrast-color: ('grays', 800),
-            rgba: .2
+            rgba: .1
         ),
 
         item-active-text-color: (

projects/igniteui-angular/src/lib/core/styles/themes/schemas/light/_navdrawer.scss

@@ -157,7 +157,7 @@ $_indigo-navdrawer: extend(
 
         item-active-background: (
             igx-contrast-color: ('grays', 700),
-            rgba: .2
+            rgba: .1
         ),
 
         item-active-text-color: (