feat: red banner for deprecating fits

[junghao]

Proposed Changes

As requested in https://github.com/GeoNet/tickets/issues/17508.

Changes proposed in this pull request:

• displaying red banner on both api-docs page and root (chart) page.

Production Changes

The following production changes are required to deploy these changes:

• None

Review

Check the box that applies to this code review. If necessary please seek help with adding a checklist guide for the reviewer.
When assigning the code review please consider the expertise needed to review the changes.

• This is a content (documentation, web page etc) only change.
• This is a minor change (meta data, bug fix, improve test coverage etc).
• This is a larger change (new feature, significant refactoring etc). Please use the code review guidelines to add a checklist below to guide the code reviewer.

Code Review Guide

Insert check list here if needed.

[bpeng]

OK