Include Robot Framework attachments in the tar file

https://gitlab.com/opentestfactory/orchestrator/-/issues/107 added the creation of a tar file to store the Robot Framework reports.
We should add in this file the test attachments.
This means that we should add any file among this list:

• ./*.png (voir https://robotframework.org/SeleniumLibrary/SeleniumLibrary.html#Capture%20Page%20Screenshot)
• ./*.jpg
• ./*.jpeg
• ./browser/screenshot/*.png (voir https://marketsquare.github.io/robotframework-browser/Browser.html#Take%20Screenshot)
• ./browser/screenshot/*.jpg
• ./browser/screenshot/*.jpeg

(. being the root directory of the project.)

Some other files can be created:

• HAR (see https://marketsquare.github.io/robotframework-browser/Browser.html#New%20Context)
• zip (see https://marketsquare.github.io/robotframework-browser/Browser.html#New%20Context)

But they are mostly for analyzing/debugging test failures.
I do not see the point to report them as a test result attachment.