update header

[ghwood]

Description

The current header uses an out-of-date style for the header and a wide mix of menu elements It would provide a more seamless experience when users (especially those new to the IETF) move across ietf.org websites by:

• adopting a general style closer to datatracker.ietf.org
• add "Author Tools" after the IETF logo in the upper left and make the logo and text link to "author-tools.ietf.org"
• use drop-down menus to group like items, perhaps:
  • About [an updated version of the content at: https://author-tools.ietf.org/about, including a link to authors.ietf.org]
  • Tools
    • I-D Diff (iddiff)
    • I-D Nits (idnits)
    • SVG Checker (svgcheck)
    • ABNF Tools
  • IETF Services
    • Author Tools API
    • BibXML
  • Other Services
    • [use the list from https://author-tools.ietf.org/about]

Note: current links to www.ietf.org and datatracker.ietf.org in the header will move to the footer.

Code of Conduct

• I agree to follow the IETF's Code of Conduct