feat: add Google Optimize support

[theBenForce]

Proposed changes

Allows developers to provide specific Google Analytics parameters, and easily provide details for Google Optimize experiments. This is accomplished by adding the $parameters object to google analytics which is used when constructing the pageview parameters.

Types of changes

• Bug fix (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 change)

Checklist

• My code follows the code style of this project
• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed

[aswetlow]

Thank you!!!