refactor: Split out @deephaven/test-utils package

[bmingles]

• Split out a @deephaven/test-utils dev package to remove jest dependencies from @deephaven/utils

resolves #2185

BREAKING CHANGE: TestUtils has been moved to new package @deephaven-test-utils. Consumers will need to install the new package as a dev dependency and update references.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 46.61%. Comparing base (1503a37) to head (eca6237).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2225      +/-   ##
==========================================
- Coverage   46.77%   46.61%   -0.17%     
==========================================
  Files         694      692       -2     
  Lines       38625    38506     -119     
  Branches     9867     9619     -248     
==========================================
- Hits        18068    17948     -120     
- Misses      20504    20547      +43     
+ Partials       53       11      -42     

Flag	Coverage Δ
unit	46.61% <ø> (-0.17%)	⬇️

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