Add `GitatrributesSupportsReadingFromHead` flag to use git v2.43.0

This issue is raised from &9006 (comment 1678741678) and #4540 (comment 1669472570)

Currently, Gialy's upstream git is at 2.42 which doesn't support reading from HEAD:.gitattributes, so we will need to wait for git 2.43 to totally remove the dependency of info/attributes.

In order to unblock development, in this issue we will add a flag GitatrributesSupportsReadingFromHead which check if the underlying git version is above or equal 2.43.

An example of coding example can be found here