Kernel: root command line option can be specified as an UUID

Format is the same as in linux
root=UUID=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX

This makes it easier to boot when computer has multiple disks installed

kernel/kernel/Storage/Partition.cpp

@@ -18,6 +18,7 @@ namespace Kernel
 		, m_device(device)
 		, m_type(type)
 		, m_guid(guid)
+		, m_guid_string(MUST(guid.to_string()))
 		, m_first_block(first_block)
 		, m_last_block(last_block)
 		, m_attributes(attr)