Fix type conversion issue with ClickActivity.LinkId

This pull request addresses the following issues:

Inconsistent pagination methods across campaign tracking methods. 
- Added GetCampaignTrackingClicks which simply wraps GetClicks for consistency and readability.

- Serialization error when reading clicks for a campaign. Link id is numerically too large to be stored as int32.
- Changed type to string for consistency with other IDs in the wrapper.