[$40] Update header to include signup buttton

[SathyaJayabal]

Update header to include signup buttton to match this change on community app
topcoder-platform/community-app#5526

cc @Oanh-and-only-Oanh

Standards

https://platform.topcoder-dev.com/model/help/copilots-link

[jmgasper]

Challenge https://www.topcoder.com/challenges/7aacf29e-0662-493f-b143-e18524a5d0f8 has been created for this ticket.

This is an automated message for ghostar via Topcoder X

[jmgasper]

Challenge https://www.topcoder.com/challenges/7aacf29e-0662-493f-b143-e18524a5d0f8 has been assigned to obog.

This is an automated message for ghostar via Topcoder X

[atelomycterus]

@jmgasper Please update the Register url if you want to configure the link with query params as mentioned in the issue(topcoder-platform/community-app#5526) or change it. The current value is https://www.topcoder-dev.com/user-selection/ in DEV:

Please apply PRs:
topcoder-platform/forums-theme#58
topcoder-platform/forums-plugins#103
#626

Thanks!

Testing

[sdgun]

Verified in Dev, the https://www.topcoder-dev.com/user-selection/ page is opened as configured now.

@atelomycterus @jmgasper Note: Now we don't have the Rainbow logo anymore in Dev.