Allow multi-browser configuration

[sheremet-va]

Clear and concise description of the problem

Currently, to run several browsers in Vitest, you need to create separate projects. Unfortunately, every project has its own browser provider and Vite server which makes it inefficient - reusing the same server could speed up tests tremendously because assets are cached.

Suggested solution

Allow passing down a list of browsers and configurations:

export default defineConfig({
  test: {
    browser: {
      provider: 'playwright',
      capabilities: [
        { browser: 'chromium', context: {}, launch: {} },
        { browser: 'firefox', context: {}, launch: {} },
        { browser: 'webkit' },
      ],
    },
  },
})

Alternative

No response

Additional context

No response

Validations

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