`xvc storage new ssh`

[Emre Sahin]

• This is different from #111.
• This uses compiled ssh library, probably https://docs.rs/ssh2/latest/ssh2/
• It requires openssl-vendored or openssl crate. (See crate's Readme). However, this brings an extra complexity in compilation. From OpenSSL docs

If the vendored Cargo feature is enabled, the openssl-src crate will be used to compile and statically link to a copy of OpenSSL. The build process requires a C compiler, perl (and perl-core), and make. The OpenSSL version will generally track the newest OpenSSL release, and changes to the version are not considered breaking changes.

• So instead of relying to this, we can make rsync one of the default features that can be used from shell. After implementing this behind a feature flag, if the user wants a native connection without rsync, they can use this.