Update SUSE banner and support left-justified text overlay

[nwmac]

Summary

Fixes #15744

Occurred changes and/or fixed issues

This PR adds the new banner (to be updated).

It also adds to brand metadata to allow the overlaid text to be left-aligned rather than centred - this is now used for the SUSE banner.

We also add the ability to specify a class name that will be added to the banner, so that a brand's stylesheet can customise the style, without defining styles that rely on the particular styles that are used in the dashboard code.

This PT also removes the small style from the banner component - we only show it in 2 places and these will now both use a single default height of 200px. This PR tweaks the styles slightly to ensure that a custom theme style does not get ignored due to CSS specificity rules.

Areas or cases that should be tested

Check homepage banner when the ui-brand is set to suse.

Screenshot/Video

Light Mode:

Dark Mode:

Note on medium screens, the welcome text overlaps the border of the circle in the image (see the R of Rancher):

Light Mode:

Dark Mode:

On smaller screen widths, we change the banner centring to left, so the text does not overlay onto the ship part of the image:

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 @nwmac . Works as advertised 🙏