[WAIT TO MERGE] Use remoteliteralinclude for code in user guide docs

[neverett]

Why are the changes needed?

Replace embedded code snippets with rli (remoteliteralinclude) directives to point to runnable example code in the Flytesnacks repo. That way, we're always pointing to tested, runnable code.

Check all the applicable boxes

• All new and existing tests passed.
• All commits are signed-off.

Related PRs

Merge flyteorg/flytesnacks#1630 first.

Docs link

New user guide with code included from flytesnacks via rli directive: https://flyte--5207.org.readthedocs.build/en/5207/user_guide/index.html

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 58.10%. Comparing base (7287470) to head (fd30192).
Report is 9 commits behind head on master.

❗ Current head fd30192 differs from pull request most recent head 044576a. Consider uploading reports for the commit 044576a to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5207      +/-   ##
==========================================
- Coverage   58.60%   58.10%   -0.50%     
==========================================
  Files         568      516      -52     
  Lines       51121    47453    -3668     
==========================================
- Hits        29958    27573    -2385     
+ Misses      18748    17622    -1126     
+ Partials     2415     2258     -157     

Flag	Coverage Δ
unittests	58.10% <ø> (-0.50%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[ppiegaze]

I checked a few of the RLIs. They seem to work well. I really like this. I think it will be a game changer for us!