Properly type config file if TypeScript is being used

[christian-bromann]

Proposed changes

This patch adds 3 changes to the config wizard:

• it creates a .ts file if typescript is used
• it types the config if typescript is used, e.g. file starts with

  export const config: WebdriverIO.Config = {

• it adds expect-webdriverio to the types list in the confirmation note

Types of changes

• Bugfix (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 not work as expected)
• Documentation update

Checklist

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• I have added proper type definitions for new commands (if appropriate)

Further comments

fixes #5944

Reviewers: @webdriverio/project-committers

[wswebcreation]

LGTM