refactor: Rename ButtonGroup to SplitButtonGroup

[bmingles]

Renaming ButtonGroup to SplitButtonGroup to avoid naming collisions with Spectrum.

resolves #2015

BREAKING CHANGE: Renamed @deephaven/components ButtonGroup to SplitButtonGroup

[dsmmcken]

Shouldn't touch ButtonOld, I have no expectation of it having compatibility. I should just refactor it out entirely.

[dsmmcken]

Did you mean to do that on Button?

[bmingles]

@dsmmcken I'm planning to do this on Button as well. ButtonOld just happened to be the first attempt since it is used in the Styleguide where I was testing.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 46.37%. Comparing base (3a6a439) to head (0b4a2f0).

❗ Current head 0b4a2f0 differs from pull request most recent head 3b8c3bc. Consider uploading reports for the commit 3b8c3bc to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1997      +/-   ##
==========================================
+ Coverage   46.34%   46.37%   +0.03%     
==========================================
  Files         673      668       -5     
  Lines       38762    38704      -58     
  Branches     9818     9799      -19     
==========================================
- Hits        17963    17949      -14     
+ Misses      20746    20702      -44     
  Partials       53       53              

Flag	Coverage Δ
unit	46.37% <100.00%> (+0.03%)	⬆️

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[mattrunyon]

What's the reason for the rename? Don't see anything here or in the ticket

[bmingles]

What's the reason for the rename? Don't see anything here or in the ticket

It's to allow us to re-export Spectrum ButtonGroup. I updated the ticket description with details.