Add warning message to login page

[ChengShi-1]

What this PR does / why we need it:

Like the description in the issue, to avoid confusion of users when they sign in, we need to add a note/alert on the Harvard SPA login page to clarify that some of the available login options are not supported.
Besides the text, I also add a navigation to sign up an account in JSF.

Which issue(s) this PR closes:

• Closes Add Warning Message to Login page #930

Special notes for your reviewer:

For next steps to apply this in production, refer to docs/KEYCLOAK_DEPLOYMENT.md, we will need to

1. npm run build-keycloak-theme, This generates dist_keycloak/dv-spa-kc-theme.jar
2. Deploy that JAR to the production Keycloak instance. Copy dist_keycloak/dv-spa-kc-theme.jar into Keycloak’s providers/ directory
3. Restart Keycloak to reload the provider/theme JAR
4. Also, Confirm the production realm is using the dataverse-spa login theme(Realm Settings -> Themes -> Login Theme -> dataverse-spa)

Suggestions on how to test this:

See how to build keycloak in this doc

Then, go to spa => sign in, the note and styled log in page should be shown

Does this PR introduce a user interface change? If mockups are available, please link/include them here:

## Is there a release notes or changelog update needed for this change?:

Additional documentation:

[coveralls]

coverage: 97.365% (+0.07%) from 97.297% — 930-add-warning-message-to-login-page into develop

[ekraffmiller]

Fyi, I removed the HDV SPA Rollout label, because we won't need this for our end of March deployment. The power users won't be logging in to the production environment, they will use Demo instead.

[ekraffmiller]

This looks good, but I think given the known issues we have with users that have '@' in their username, I think it would be good to update the message to 'Note about CILogin', rather than a note about Github, Google and Orchid users.

[ChengShi-1]

Hi @ekraffmiller , I just changed the text to "CILOGON options"

[ekraffmiller]

This looks good! Just thinking that in order to easily remove it when it's no longer needed, can you create a separate component for the warning message?