C++ code should be in the autoware namespace

[esteve]

Checklist

• I've read the contribution guidelines.
• I've searched other issues and no duplicate issues were found.
• I've agreed with the maintainers that I can plan this task.

Description

Current C++ code does not follow a unified convention for namespaces. According to the Google C++ Style Guide (which the ROS Style guide is based upon) code must be under a namespace that matches the name of the project https://google.github.io/styleguide/cppguide.html#Namespaces

Purpose

• Avoid conflicts with other non-Autoware projects
• Highlight that our packages are part of autoware

Possible approaches

The most straightforward approach is to just add all software to the autoware namespace, however, we might want to also add another subnamespace for the component the code is part of (i.e. perception, localization, etc.)

Definition of done

All the code is under either the autoware namespace or a subnamespace of it

[esteve]

Related discussion: https://github.com/orgs/autowarefoundation/discussions/4097#discussioncomment-8347308

[xmfcx]

Over 2 options:

1. autoware::package_name
2. autoware::component_name::package_name

My vote would be on Option 1.
Reasons:

• Easier to type and reduced complexity
• Easier to move package over component folders (if we want to change its component category) (ease of refactoring)
• Is not necessary to have the additional namespace since we don't expect the packages within the Autoware to clash.

cc. @yukkysaito @mitsudome-r @isamu-takagi @TakaHoribe

[esteve]

@xmfcx I agree, I prefer to keep hierarchies as flat as possible

[esteve]

Closing, superseded by #4569