foreach: expose the name of the default remote

[dmerejkowsky]

trafficstars

Something like TSRC_CLONE_REMOTE_NAME maybe? We already have TSRC_CLONE_URL.

Or use TSRC_DEFAULT_REMOTE_NAME and TSRC_DEFAULT_REMOTE_URL ?

[Lecrapouille]

@dmerejkowsky Do you mean the table in this doc https://dmerejkowsky.github.io/tsrc/guide/foreach/#using_repo_and_manifest_data ? TSRC_CLONE_URL is not described. And in 350 can you reply why git rebase is destructive to help me to understand !