feat(docs): enable navbar

[foskey51]

Which issue does this PR close?

• Closes Website: dark mode toggle #18284.

What changes are included in this PR?

I've enabled the navbar, which is required to use dark-light mode toggle and made following changes in the ui

• Removed the existing logo in the side-bar (as it was redundant)
• Removed search bar in the side-bar (as it was conflicting with navbar's search widget)

[Jefffrey]

Some things I noticed:

• Toggle has 3 states (and 3 different icons)
• Theme is remembered per page, not globally; e.g. if I set light mode (default is dark) on home/index page, and I navigate to another page, that page will be dark but when I navigate back to home it'll be light
• The More menu on the navbar doesn't play well given it's length, might be better off removing it
• I also prefer removing the other links on the navbar (e.g. License, Donate) given they are also at the top of the sidebar; either keep the sidebar ones or keep only the navbar ones to remove this duplication

[foskey51]

hey @Jefffrey

• Your are seeing 3 states (light, dark, system-theme) because it's default and there's no implicit way to remove the system-theme aka third state you can refer this issue, explicitly removing it might cause unexpected behavior.

• The "theme is remembered per page" is caused due to accessing the index.html directly as file:///xyz/datafusion/docs/build/html/index.html so now dev-tools>storage>local-storage variables responsible for theming are tracked by dynamically changing file name which ends-up getting a new default state for each file. To resolve this, try serving it via a http server like

#run it in docs/ dir
python3 -m http.server 8000

#access the docs build at
http://localhost:8000/build/html/index.html

now local storage tracks it by host-name aka http://localhost:8000. So this shouldn't be an issue in production, as it will be tracked by domain name.

• I've removed the links displayed in the navbar.