[documentation] restructure Prestissimo developer documentation in Presto docs

[steveburnett]

Description

Create a new top-level topic in Presto docs for Prestissimo Developer Guide, parallel to the existing Developer Guide in the Presto docs. Specific actions of this restructuring:

• create a new top-level category in Presto documentation "Prestissimo Developer Guide"
• move develop/presto-native.rst into new directory "prestissimo"
• create new prestissimo.rst index file for the new directory "prestissimo"
• rename prestissimo/presto-native.rst as prestissimo/prestissimo-features.rst
• add table of contents to prestissimo/prestissimo-features.rst, like overview/concepts.rst has

Motivation and Context

Restructuring the documentation, specifically moving the content in develop/presto-native.rst out of the Presto developers guide section of the documentation provides a top-level category for Prestissimo developer documentation, allows for sub-pages within Prestissimo developer documentation, and provides an area to grow the much-needed topic of Prestissimo developer documentation.

Impact

Documentation.

Test Plan

Local build of the new and modified doc files.

Screenshots of the local build of the docs showing changes:

1. Presto Developer Guide index page, showing the absence of the removed Prestissimo - Presto native page.

2. Prestissimo Developer Guide index page - defining who this document is for, cautioning that it is in active development, introducing what is Prestissimo, and showing the two sub-pages "Prestissimo Features" and "Prestissimo Limitations" on the page itself, and also in the left column nav bar.

3. Prestissimo Features sub-page, with new internal table of contents that develop/presto-native.rst did not have.

Contributor checklist

• Please make sure your submission complies with our development, formatting, commit message, and attribution guidelines.
• PR description addresses the issue accurately and concisely. If the change is non-trivial, a GitHub Issue is referenced.
• Documented new properties (with its default value), SQL syntax, functions, or other functionality.
• If release notes are required, they follow the release notes guidelines.
• Adequate tests were added if applicable.
• CI passed.

Release Notes

Please follow release notes guidelines and fill in the release notes below.

== RELEASE NOTES ==

General Changes
* Add Prestissimo Developer Guide topic to the Presto documentation

[aditi-pandit]

Thanks @steveburnett