Finalize the field type for pointcloud

[mitsudome-r]

Description

The output type of lidars should be clarified.

Purpose

The message information from the sensor drivers should be available for users to implement their own drivers.
Relate discussion: autowarefoundation/autoware#2480

Definition of done

• The details of output message from sensor drivers should be available in documentation

[mitsudome-r]

We will be finalizing this in this week's Autoware Architecture WG meeting along with other sensor_msgs

[mitsudome-r]

We have discussed on this in the Architecture WG
autowarefoundation/autoware#2626

Lidar:
We still need to agree on pointfield definition
PointXYZI+LaserChannel+Time
Do we want to remove laser channel after preprocessing is done within sensor module?
We can still allow additional fields if required

@xmfcx will create a PR to design document.

[xmfcx]

autowarefoundation/autoware-documentation#180 This is being worked on.