Ext4Pkg: Move unicode collation initialization to Start()

There have been reports[1] of failures to boot due to unicode collation
protocols not being available at Ext4Dxe load time. Therefore, attempt
to initialize unicode collation at Start() time, like done previously in
FatPkg/EnhancedFatDxe. By doing so, we move collation initialization
to BDS, where the module responsible for protocol installation should
have already been loaded and ran.

[1]: https://edk2.groups.io/g/devel/message/100312



Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Marvin Häuser <mhaeuser@posteo.de>
Fixes: d9ceedca ("Ext4Pkg: Add Ext4Dxe driver.")
Signed-off-by: Pedro Falcato <pedro.falcato@gmail.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Marvin Häuser <mhaeuser@posteo.de>