Update SUSE login banner and support custom image style

[nwmac]

Summary

Fixes #15744

Note: This PR is based off of #15716 - which should be reviewed and merged first.

Occurred changes and/or fixed issues

This PR adds new dark and light themed banner images for the login screen.

Additionally, it adds brand metadata and uses this in login.vue so that the SUSE them can align the graphic to the left, which ensures

Technical notes summary

Modifies login.vue to support extra metadata from the theme:

Logo file to be shown in place of the Howdy! text
Translation string to use in place of Welcome to Rancher
Class name to be applied to the logo (when used) to allow customisations by the theme, without having to rely on specify class names/structure in the code
The PR updates metadata.json for the SUSE theme, to use the Prime logo, to change the text and to set the styling (See below).

Areas or cases that should be tested

Check login screen for Prime and Community.

Note: Set ui-brand to suse to test the Prime branding.

Screenshot/Video

Light mode:

Dark mode:

Checklist

• The PR is linked to an issue and the linked issue has a Milestone, or no issue is needed
• The PR has a Milestone
• The PR template has been filled out
• The PR has been self reviewed
• The PR has a reviewer assigned
• The PR has automated tests or clear instructions for manual tests and the linked issue has appropriate QA labels, or tests are not needed
• The PR has reviewed with UX and tested in light and dark mode, or there are no UX changes
• The PR has been reviewed in terms of Accessibility
• The PR has considered, and if applicable tested with, the three Global Roles Admin, Standard User and User Base

[aalves08]

LGTM

brand suse

without brand