refactor: Move Panel into @deephaven/dashboard

[mofojed]

• Move Panel into @deephaven/dashboard, removing functionality depending on core plugins and keeping in CorePanel in the dashboard-core-plugins package
• Should be no breaking changes, as dashboard-core-plugins re-exports the components that were removed
• Allows plugins (such as deephaven.ui) to simply use the Panel component without having to depend on other core plugins
• Tests pass, ran a smoke test with latest version of deephaven.ui to ensure functionality still worked

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 72.72727% with 9 lines in your changes missing coverage. Please review.

Project coverage is 47.24%. Comparing base (9de971f) to head (d27cb92).

Files with missing lines	Patch %	Lines
...es/dashboard-core-plugins/src/panels/CorePanel.tsx	67.85%	9 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2304      +/-   ##
==========================================
- Coverage   47.31%   47.24%   -0.07%     
==========================================
  Files         723      726       +3     
  Lines       39772    39785      +13     
  Branches    10144     9955     -189     
==========================================
- Hits        18819    18798      -21     
- Misses      20899    20976      +77     
+ Partials       54       11      -43     

Flag	Coverage Δ
unit	47.24% <72.72%> (-0.07%)	:arrow_down:

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[mofojed]

@mattrunyon I retested and rebased this. Found one issue with TabEvent deprecated export in dashboard-core-plugins, should be resolved now with no breaking changes.