PPP-3308 - Migration Tool does not migrate double byte files and folders

What was done:
1) changed path encode and decode routines to encode invalid symbols
2) added id encode routine as it was called once but id may start with
digit which is not valid for path anymore
3) added unit tests  to validate different usage of routines
Merge pull request #1774 from kolinus/PPP-3308

PPP-3308 - Migration Tool does not migrate double byte files and folders