Allow passing request config to VBase's getJSON method

[mairatma]

What is the purpose of this pull request?

Allow passing request options when calling VBase's getJSON method.

What problem is this solving?

Today it isn't possible to send custom per-request options for VBase's getJSON method, so we can't use the forceMaxAge option per request, for example. This extra param will also allow passing a new request config that will added in a subsequent PR.

How should this be manually tested?

• Build the codebase and verify that there were no errors.
• Link this npm package into an app, within a linked workspace, and make sure that vbase calls are working as before.

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Requires change to documentation, which has been updated accordingly.