Added optional toggle for adding of TrackedPoseDriver

[MattGrayUL]

Summary

Allow users that do not require a TrackedPoseDriver to optionally turn off the automatic creation of TrackedPoseDrivers from the LeapXRServiceProvider

Contributor Tasks

These tasks are for the merge request creator to tick off when creating a merge request.

• Pair review with a member of the QA team.
• Add any release testing considerations to the MR for the next release.
• Check any relevant CHANGELOG files have been updated.
• Ensure documentation requirements are met e.g., public API is commented.
• Consider any licensing/other legal implications for this MR e.g. notices required by any new libraries.
• Add any relevant labels such as breaking to this MR.
• If this MR closes a Jira issue, make sure the fix version on the JIRA issue is set to the correct one.

Reviewer Tasks

Add any instructions or tasks for the reviewer such as specific test considerations before this can be merged.

Use emojis in review threads to communicate intent and help contributors.

• Code reviewed.
• Non-code assets e.g. Unity assets/scenes reviewed.
• Documentation has been reviewed. Includes checking documentation requirements are met and not missing e.g., public API is commented.
• Checked and agree with release testing considerations added to MR for the next release.

Closes JIRA Issue

Closes UNITY-984