Shift site build to use monorepo and gh-pages

[bitsondatadev]

Revert back to using the site directory which contains the monorepo of the site and versioned docs. Adds in the site styling to look like the current Apache Iceberg site. Adds the main build infrastructure.

I gleaned info from this PR, this PR, this PR and a bit off of this deploy script.

Here is a link to the gh-pages in my branch: https://bitsondatadev.github.io/iceberg/

I will be doing another PR to handle the following task items. when we get some eyes on the current site and if anyone sees any issues.

Also move back to using the asf infra standards including the asf-site branch.

This PR will be moving /docs/docs/nightly/ up to /docs/nightly/ based on some bad state that happened when we pulled the versioned docs into the worktree. So most of the changed files are just those files being moved.

[RussellSpitzer]

not a huge deal but may help to pass through an error message so we know which arg is missing

Echo "Missing an argument: $2 "

[RussellSpitzer]

Saw a few nits in the docs, but worked well locally for me. Worktree code seems to working as expected but i'm not an expert in their usage for something like this.

[Fokko]

Some small comments. I did a local build and it all works. The UI needs a bit of rework, but we can do that in a separate PR. What I do think is that we need to add 1.4.3 in https://github.com/apache/iceberg/tree/docs before merging this.

[Fokko]

Not for this PR, but it would be good at some point to just include the spec from the repository itself.

[bitsondatadev]

@Fokko I updated after your comments!

[Fokko]

This looks great, and I don't see any open comments. If there is anything we can follow up on in a separate PR. I'll go ahead and rebase and merge this 🚀 Thanks for the reviews @rdblue, @RussellSpitzer, and a special thanks to @bitsondatadev for taking care of the docs!