feat: Add before:run event

[chrisbreiding]

NOTE: Merge #9595 first and change base branch before merging this

• Addresses TR-538
• Partially addresses Add new plugin events 'before:spec', 'after:spec', 'before:run', 'after:run' #6665

User facing changelog

• You can now listen to a before:run event in the plugins file. See the documentation for more information (TODO: link to doc).

Additional details

• The event fires before the run.
• It only fires in run mode.
• If running parallel, it will run for each machine running.
• The event handler receives one argument, an object with details about the run.

on('before:run', (details) => {
  // details:
  // {
  //   browser: {
  //     name: 'electron',
  //     family: 'chromium',
  //     version: '87.0.4280.67',
  //     // ... more properties
  //   },
  //   config: {
  //     projectName: 'my-app',
  //     baseUrl: 'http://localhost:1234',
  //     // ... more properties
  //   },
  //   cypressVersion: '6.1.0',
  //   group: 'group-1',
  //   parallel: false,
  //   specs: [
  //     {
  //       name: 'login_spec.js',
  //       relative: 'cypress/integration/login_spec.js',
  //       absolute: '/Users/janelane/my-app/cypress/integration/login_spec.js',
  //       specType: 'integration'
  //     }
  //   ],
  //   specPattern: [ 'cypress/integration/login_spec.js' ],
  //   system: { osName: 'darwin', osVersion: '19.6.0' },
  //   tag: 'tag-1'
  // }

})

PR Tasks

• Have tests been added/updated?
• Has the original issue or this PR been tagged with a release in ZenHub?
• Has a PR for user-facing changes been opened in cypress-documentation? Add doc for before:run event cypress-documentation#3425
• Have API changes been updated in the type definitions?
• N/A Have new configuration options been added to the cypress.schema.json?

[cypress-bot]

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[cypress]

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Test summary

9162 • 0 • 118 • 3 • 1

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Run details

Project	cypress
Status	Passed
Commit	39e798e
Started	Dec 21, 2020 5:30 PM
Ended	Dec 21, 2020 5:43 PM
Duration	12:38 💡
OS	Linux Debian - 10.5
Browser	Multiple

View run in Cypress Dashboard ➡️

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Flakiness

	cypress/integration/retries.ui.spec.js		1
1	runner/cypress retries.ui.spec > opens attempt on each attempt failure for the screenshot, and closes after test passes

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The base branch was changed.

[cypress-bot]

Released in 6.2.0.

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