Add google filter for time-slots

[keavan-andreassen]

Description

This PR adds the google filter to time-slots. This filter uses the provided Google access token to only fetch time-slots that match the availability associated with the access token.

Motivation and context

This change is required to allow time-slots to be filtered using Google calendar events. The API uses the Google access token to fetch Google events, which are then used to check for conflicts.

How has this been tested?

I have added a new test to the set of time-slots tests. It is focused on testing the new time-slot filter google. The test case is:

• will set a google token filter

Screenshots (if appropriate)

Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

• 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:

Go over all the following points, and put an x in all the boxes that apply.

Please, please, please, don't send your pull request until all of the boxes are ticked. Once your pull request is created, it will trigger a build on our continuous integration server to make sure your tests and code style pass.

• I have read the CONTRIBUTING document.
• My pull request addresses exactly one patch/feature.
• I have created a branch for this patch/feature.
• Each individual commit in the pull request is meaningful.
• I have added tests to cover my changes.
• If my change requires a change to the documentation, I have updated it accordingly.

If you're unsure about any of these, don't hesitate to ask. We're here to help!