Some day in the past the Slash encode option was added to Onedrive
encoder so it began to encode slashes in file names rather then treat
them as path separators.
This patch adapts benchmark test cases accordingly.
Fixes#5659
Instead of only adding SCSU, add it as an existing table.
Allow direct SCSU and add a, perhaps, reasonable table as well.
Add byte interfaces that doesn't base64 encode the URL as well with `EncodeBytes` and `DecodeBytes`.
Fuzz tested and decode tests added.
Allows to compress short arbitrary strings and returns a string using base64 url encoding.
Generator for tables included and a few samples has been added. Add more to init.go
Tested with fuzzing for crash resistance and symmetry, see fuzz.go
