fix(tooling): replace Rollup with Webpack for bundling of meetings widget

[Riteshfyi]

COMPLETES #https://jira-eng-gpk2.cisco.com/jira/browse/SPARK-767471

This pull request addresses

Removes rollup & moves to webpack for the bundling of meetings widget.

by making the following changes

By Removing rollup config and Updating the webpack.config.js & package.json.

Change Type

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Tooling change
• Internal code refactor

The following scenarios were tested

• The testing is done locally with samples, then tried consuming from another demo project.
  < ENUMERATE TESTS PERFORMED, WHETHER MANUAL OR AUTOMATED >

The GAI Coding Policy And Copyright Annotation Best Practices

• GAI was not used (or, no additional notation is required)
• Code was generated entirely by GAI
• GAI was used to create a draft that was subsequently customized or modified
• Coder created a draft manually that was non-substantively modified by GAI (e.g., refactoring was performed by GAI on manually written code)
• Tool used for AI assistance (GitHub Copilot / Other - specify)
  • Github Copilot
  • Other - Cursor
• This PR is related to
  • Feature
  • Defect fix
  • Tech Debt
  • Automation
  • Tooling

Checklist before merging

• I have not skipped any automated checks
• All existing and new tests passed
• [] I have updated the testing document
• I have tested the functionality with amplify link

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[Shreyas281299]

Based on the webpack config I feel here the mode should be development

Suggested change

	"demo:build": "webpack ./demo/App.jsx --env buildType=demo --mode production",
	"demo:build": "webpack ./demo/App.jsx --env buildType=demo --mode development",