support msg.stamp as an alternative to msg.header.stamp

[jobafr]

User-Facing Changes
Support plotting with (msg).stamp in addition to (msg).header.stamp, for messages that don't wrap their timestamp in a std_msgs/Header. A similar workaround exists already for MarkerArray.

Description

Checklist

• The web version was tested and it is running ok
• The desktop version was tested and it is running ok
• I've updated/created the storybook file(s)
• The release version was updated on package.json files

[laisspportugal]

Hello @jobafr,

Thank you for your contribution! We really appreaciate that.
Can you please review the following points?

• Please add an unit tests to cover this scenario
• Verify lint errors mentioned in the pipeline (you can check them locally by running yarn run lint:ci)
• We also appreciate if you use our contribution guidelines to increase the version numbers.

Thanks in advance

[laisspportugal]

Hello @jobafr,
Due the lack of answers this PR will be close in the end of this week if the changes are not addressed.
Thanks in advance