Convert all webview-ui tests: jest -> vitest

[cte]

Description

Related: #4607

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Important

Convert all webview-ui tests from Jest to Vitest, updating configurations, mocks, and test file naming conventions.

• Test Conversion:
  • Convert all test files in webview-ui from Jest to Vitest, including spec.ts and spec.tsx files.
  • Update test imports and mocks to use vi instead of jest.
  • Remove Jest-specific setup files like setupTests.tsx and replace with vitest.setup.ts.
• Configuration:
  • Add vitest.config.ts for Vitest configuration, specifying test environment, setup files, and file inclusion patterns.
  • Update package.json scripts to use vitest instead of jest for running tests.
• Mocking and Setup:
  • Replace Jest mocks with Vitest mocks using vi.mock().
  • Add vitest.setup.ts to configure global mocks and environment settings for Vitest.
  • Remove Jest-specific mock files and configurations.
• Miscellaneous:
  • Update .dockerignore to remove jest.config* entries.
  • Ensure all test files are renamed from .test.tsx to .spec.tsx to align with Vitest conventions.

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