librespeed-cli-rust: add new package

librespeed-cli-rust: add new package

Rust port of librespeed-cli for 32-bit PowerPC targets not supported by
the Go implementation, such as CZ.NIC Turris 1.x.

The CLI output of --list and --csv-header matches the Go client, so it
can be used as a drop-in replacement. Both implementations install
/usr/bin/librespeed-cli and therefore PROVIDES/CONFLICTS are set
accordingly.

Use libopenssl instead of rustls' ring backend, which has significantly
better AES-GCM performance on big-endian PowerPC.

Signed-off-by: Josef Schlehofer <redacted>