fuel-upgrade: improve bootstrap logic

Also the commit introduce next changes:

* remove legacy stuff: CopyFromUpdate class and some utils
* add possibility to set custom undo rules for action
* add symlink action

Implements blueprint upgrade-to-5-1

Change-Id: I8d6c73f6ac4464a7859b539a85234aaf6a551f09
Merge "fuel-upgrade: improve bootstrap logic"