avro

AVRO-3529: Rust: Use git-archive to make a source distribution of the Rust SDK (#1713)

* AVRO-3529: Rust: Use git-archive to make a source distribution of the Rust SDK

Re-order the modules in the main Cargo.toml so that 'cargo ...' commands
are executed in the preferred order.

Export special Rust env vars for better diagnostics for the interop
tasks.

Signed-off-by: Martin Tzvetanov Grigorov <mgrigorov@apache.org>

* AVRO-3529: Export the RUST_** env vars only for the cargo command execution

Signed-off-by: Martin Tzvetanov Grigorov <mgrigorov@apache.org>