feat: DH-19146: ElementPlugin mapping hook

[jnumainville]

Will also need deephaven/deephaven-plugins#1201 for the plugin side, but this implements a hook that pulls the necessary mapping for element plugins

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 44.64%. Comparing base (7785090) to head (e783149).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2477      +/-   ##
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+ Coverage   44.62%   44.64%   +0.02%     
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  Files         759      760       +1     
  Lines       42550    42564      +14     
  Branches    10693    10696       +3     
==========================================
+ Hits        18989    19004      +15     
+ Misses      23550    23549       -1     
  Partials       11       11              

Flag	Coverage Δ
unit	44.64% <100.00%> (+0.02%)	⬆️

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[Copilot]

Pull Request Overview

Adds support for extracting element-specific plugins by introducing a new hook, utility function, type definitions, and associated tests.

• Introduces useElementPluginMapping hook to build a mapping of element names to their React components from the plugin context.
• Extends PluginUtils and PluginTypes with ElementPlugin support and the getElementPluginMapping helper.
• Adds unit tests for the new hook and getElementPluginMapping function.

Reviewed Changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/plugin/src/useElementPluginMapping.tsx	New hook to retrieve element plugin mapping
packages/plugin/src/index.ts	Exports the new hook
packages/plugin/src/UseElementPluginMapping.test.ts	Tests for the new hook
packages/plugin/src/PluginUtils.tsx	Added getElementPluginMapping and logging
packages/plugin/src/PluginUtils.test.tsx	Tests for getElementPluginMapping
packages/plugin/src/PluginTypes.ts	Defined ElementPlugin type and isElementPlugin

Comments suppressed due to low confidence (2)

packages/plugin/src/UseElementPluginMapping.test.ts:1

• [nitpick] Test file name casing (UseElementPluginMapping.test.ts) differs from the hook file (useElementPluginMapping.tsx). Consider aligning test file name to useElementPluginMapping.test.ts for consistency.

import { renderHook } from '@testing-library/react-hooks';

packages/plugin/src/PluginUtils.tsx:89

• React is not imported in this file, but React.ComponentType is used. Add import { type ComponentType } from 'react'; or import React from 'react'; at the top.

): Map<string, React.ComponentType<unknown>> {

[mofojed]

A few small things to clean up

[mofojed]

Couple other things I noticed after reviewing the deephaven-plugins side.