Add Support for Custom Domains

[drewf7]

Checklist

• [X] You created a branch from develop branch.
• [X] You PR is raised on develop branch and not onmain.
• [X] You have read the Contribution Guidlines before creating this PR.

Description of the Change

Add support in the library for the optional "customDomain" value to be passed in to allow users to specify that the library should use a customer vanity domain for IDX logins rather than the .hub.loginradius.com variant.

This is required for third party cookies to work with customer domains.

Alternate Designs

N/A

Risk Impact

Risk should be very low as the new parameter is optional so all existing use cases can ignore it.

Verification Process

We built a version of the library with these changes included. First verifying that omission of the new parameter results in identical behavior as before (sending users to .hub.loginradius.com).

We also verified that including the new customDomain parameter resulted in users being sent to our custom IDX domain for sign in.

Release Notes

• Add support for customDomain to be specified in library

[drewf7]

Hi @mohammed786,

Sorry to bother but I wanted to follow up on this as we are continuing to have to deploy a customized version of this package to our sites.

Is there anything I've missed that is needed to start the review process?

Thanks!