[Pointer] Display play area sized cursor option on all pointers with boundary collision detection

[thestonefox]

Project a play area sized cursor on the floor where the pointer is pointing to to show where the play area will be after teleport.

The cursor will also have a trigger collider on it so if it collides with any other objects it can set a flag to say a collision has happened and if a collision is happening then don't throw the set new teleport location.

This value can also be used by extended pointers to change the colour of their beam depending on whether the location is valid or invalid.

Can get the size of the play area from the SteamVR_PlayArea script as it contains a public Vector3[] verticies variable which contains the relevant points for drawing the play area boundaries, so can use this numbers to create the cursor at the right size.

[thestonefox]

Completed with 87c6ebb