fix: Context menu using stale selection

[ericlln]

• Although we handle the case where the grid is right-clicked outside of the current selection in GridSelectionHandler.ts, where the new selection will be updated to the row the cursor is on, state changes are batched in event handlers so IrisGridContextMenuHandler.tsx will be using a stale value for selectedRanges when it runs.
• To fix this we can implement the exact same logic in both components, such that the selected ranges used in onContextMenu in IrisGridContextMenuHandler.tsx will be the same as what onContextMenu in GridSelectionHandler.ts will set it to after all handlers have ran.

Test Snippet (any table will work though)

from deephaven import empty_table, input_table
source = empty_table(10).update(["X = i", "Y = i"])
result = input_table(init_table=source)

Before this change, it was seen that right clicking any cell when the table first opens will not produce the full context menu as expected, and only subsequent clicks will open the full context menu (probably for the wrong cell).

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.

Project coverage is 46.83%. Comparing base (0f4f238) to head (27a9dad).

Files with missing lines	Patch %	Lines
...d/src/mousehandlers/IrisGridContextMenuHandler.tsx	83.33%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2407   +/-   ##
=======================================
  Coverage   46.83%   46.83%           
=======================================
  Files         711      711           
  Lines       39307    39313    +6     
  Branches     9822     9825    +3     
=======================================
+ Hits        18408    18413    +5     
- Misses      20888    20889    +1     
  Partials       11       11           

Flag	Coverage Δ
unit	46.83% <85.71%> (+<0.01%)	⬆️

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