DON-1156: Add exception for low contrast accessibility rule.

May be a good rule but I want to get the checks passing with the site
as-is so we can detect regressions before thinking about fixing things.

Author: bdsl

steps/HomePage.ts

@@ -14,5 +14,7 @@ Given(
 Then(
     /^there should be no accessibility violations detected$/,
     async function () {
-    await checkNoAccessibilityViolations();
+    await checkNoAccessibilityViolations(
+        {withAngularStepperException: false, withSalesforceHeaderException: false, withContrastRatioException: true}
+    );
 });

support/a11y.ts

@@ -6,7 +6,7 @@ import AxeBuilder from '@axe-core/webdriverio';
  * incompletes.
  */
 export default async function checkNoAccessibilityViolations(
-    options = {withAngularStepperException: false, withSalesforceHeaderException: false}
+    options = {withAngularStepperException: false, withSalesforceHeaderException: false, withContrastRatioException: false}
 ){
     console.log('Running Axe accessibility check...');
 
@@ -30,6 +30,11 @@ export default async function checkNoAccessibilityViolations(
         builder.exclude('header.lf-header_navigation');
     }
 
+    if (options.withContrastRatioException){
+        // known issue of low contrast in footer
+        builder.exclude('#footer-primary-heading');
+    }
+
     const result = await builder.analyze();
 
     const violationCount = result.violations.length;