Add id and visibility_flags fields to projector msg

[iche033]

Desired behavior

The projector msg is missing a couple of fields

• id: Projector entity id, similar to the ids in other entities, e.g. visual
• visibility_flags: Allows projector (or projected pattern rather) to be visible to cameras with matching visibility mask, see sdf spec

Implementation suggestion

Add the following fields to the projector.proto msg:

uint32 id
uint32 visibility_flags

Additional context

There are a couple of todo notes in gz-sim related to this:

• https://github.com/gazebosim/gz-sim/blob/d2d4ec9b4af5813f7247a417a3b096124bf2ca6a/src/Conversions.cc#L1790
• https://github.com/gazebosim/gz-sim/blob/d2d4ec9b4af5813f7247a417a3b096124bf2ca6a/src/systems/scene_broadcaster/SceneBroadcaster.cc#L1103