Add GT.write_html() as a helper function for easier HTML output

[jrycw]

Hello team,

I've noticed that some users expect an easier way to interact with our tables. While GT.as_raw_html() is great, it doesn’t fully meet those expectations. To address this, I’d like to propose adding GT.write_html() as a helper function, simplifying the process of writing the table’s HTML directly to a file without needing to use open().

I believe this is a useful addition, and if necessary, we could even rename it to GT._write_html() for unofficial use.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.87%. Comparing base (06b1408) to head (ceb8e60).
Report is 39 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #485      +/-   ##
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+ Coverage   87.86%   87.87%   +0.01%     
==========================================
  Files          42       42              
  Lines        4852     4859       +7     
==========================================
+ Hits         4263     4270       +7     
  Misses        589      589              

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[jrycw]

I've found that utilizing the parameters of GT.as_raw_html() might be a better approach. I suggest we keep the make_page and all_important parameters undocumented, similar to how it's done in GT.as_raw_html().