fix(navdrawer): optimize the side padding and margin

Author: MPopov

projects/igniteui-angular/src/lib/core/styles/components/navdrawer/_navdrawer-theme.scss

@@ -158,6 +158,7 @@
 
     $drawer-icon-size: rem(24px);
     $drawer-item-margin: rem(8px);
+    $text-side-padding: rem(8px);
     $drawer-item-min-h: auto;
     $drawer-item-max-h: rem(48px);
     $drawer-item-min-w: rem(32px);
@@ -320,15 +321,15 @@
 
         > igx-icon + span {
             @if $variant == 'indigo-design' {
-                margin-#{$left}: rem(28px);
+                margin-#{$left}: calc(32px - #{$text-side-padding});
             } @else {
                 margin-#{$left}: rem(32px);
             }
         }
 
         span {
             @if $variant == 'indigo-design' {
-                padding-#{$left}: rem(8px);
+                padding-#{$left}: $text-side-padding;
             }
         }