[WIP] Update uvdata tutorial

[jpober]

Description

Updates to the tutorial to make it more pedagogical and more consistent with modern pyuvdata

Motivation and Context

Our tutorial was not well-ordered from a pedagogical point of view (e.g. beginning with files conversions). Subsections have been reordered to (hopefully) make a more useful document for a new user to sit down and work through. References to older versions of pyuvdata have also largely been removed.

Closes #1341

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation change (documentation changes only)
• Version change
• Build or continuous integration change

Checklist:

• I have read the contribution guide.
• My code follows the code style of this project.

Documentation change checklist:

• Any updated docstrings use the numpy docstring format.
• If this is a significant change to the readme or other docs, I have checked that they are rendered properly on ReadTheDocs. (you may need help to get this branch to build on RTD, just ask!)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.93%. Comparing base (5ea0614) to head (eb3b412).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1534   +/-   ##
=======================================
  Coverage   99.93%   99.93%           
=======================================
  Files          63       63           
  Lines       21758    21758           
=======================================
  Hits        21743    21743           
  Misses         15       15           

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[bhazelton]

I'll work on the todos. I found a couple other minor things in my read through.

[bhazelton]

I think we need a short paragraph describing the idea of phasing, mentioning the types of phase centers and pointing to the phasing memo for more information.