phases: simplify phase exchange and movement over pushkey
The code now only exchange draft root and only care about movement related to
public//draft boundary.
There is multiple reason to simplify this code:
* Secret are never discovered anymore
* We decided to not support more the three existing phase
Removing phase index from pushkey (if ever decided) will be made in another commit.
<Include>
<?if $(var.Platform) = "x64" ?>
<?define IsX64 = yes ?>
<?else?>
<?define IsX64 = no ?>
<?endif?>
</Include>