RAR: Add sample files

[Mingun]

Sample files that I use when implement https://github.com/kaitai-io/kaitai_struct_formats/pull/493. Each archive contains the same file tree:

+-folder
|  +- nested-empty-folder
|  '- file
'- empty.txt

compress<0-5>.rar

Archives with different compression levels from none to highest

compress-parts.part<1-2>.rar

Multi-volume archive. First volume has inexplicable 9 zero bytes at the end, so is not parsable by rar.ksy

compress3-encrypted-password.rar

Fully encrypted archive (with archive structure) with default compression level. Password is "password"

compress3-restore-info10%.rar

Archive was created with 10% of recovery information and default compression level

compress3-solid-rights-time-comment.rar

Archive was created as solid, store all file timestamps, has archive comment "Archive comment" and default compression level

compress3-sfx.exe

Archive was created with self-extraction module