fix(select): show focus indicator even with validation errors (#3743)

Fixes #3742

Author: jefersonestevo

src/lib/select/_select-theme.scss

@@ -14,7 +14,7 @@
       color: mat-color($primary);
     }
 
-    .mat-select.ng-invalid.ng-touched:not(.mat-select-disabled) & {
+    .mat-select:not(:focus).ng-invalid.ng-touched:not(.mat-select-disabled) & {
       color: mat-color($warn);
     }
   }
@@ -26,7 +26,7 @@
       background-color: mat-color($primary);
     }
 
-    .mat-select.ng-invalid.ng-touched:not(.mat-select-disabled) & {
+    .mat-select:not(:focus).ng-invalid.ng-touched:not(.mat-select-disabled) & {
       background-color: mat-color($warn);
     }
   }
@@ -38,7 +38,7 @@
       color: mat-color($primary);
     }
 
-    .mat-select.ng-invalid.ng-touched:not(.mat-select-disabled) & {
+    .mat-select:not(:focus).ng-invalid.ng-touched:not(.mat-select-disabled) & {
       color: mat-color($warn);
     }
   }