fix: set the value of testingType in project-ct

[elevatebart]

• Closes Forced to return config in the plugins file even I don't change it #16860

User facing changelog

Before this PR launching cypress open-ct (Component Testing) with the function exported by cypress/plugins/index.js returning nothing would yield a "No test found" error.
Now we can omit this return config if it is not changed in the function.

Additional details

const path = require('path')
const { startDevServer } = require('../dist')

module.exports = (on, config) => {
  on('dev-server:start', async (options) => {
    return startDevServer({
      options,
      viteConfig: {
        configFile: path.resolve(__dirname, '..', 'vite.config.ts'),
      },
    })
  })

  return config; // << this statement is not necessary anymore
}

The main file to review is the last one: project-ct.ts
The rest are examples updates and changes to scaffolding with create cypress-tests to reflect the simplified setup.

How has the user experience changed?

Before: with no return config every spec file would yield the error below

After: tests are running with or without the return config

PR Tasks

• Have tests been added/updated?
• Has the original issue or this PR been tagged with a release in ZenHub?

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[cypress]

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Test summary

17994 • 0 • 214 • 7 • 0

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Run details

Project	cypress
Status	Passed
Commit	f41c8b6
Started	Jun 10, 2021 12:21 AM
Ended	Jun 10, 2021 12:31 AM
Duration	10:55 💡
OS	Linux Debian - 10.8
Browser	Multiple

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[lmiller1990]

LGTM, one comment!