avro

[AVRO-3507] Implement Single Object reader (#1681)

* Readers

* unit tested

* interop tested

* Update lang/rust/avro/src/reader.rs

Co-authored-by: Martin Grigorov <martin-g@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: Martin Grigorov <martin-g@users.noreply.github.com>

* one read for interop+ error message

* AVRO-3507: Improve an error message in a unit test

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

* AVRO-3507: Better variable names and error messages

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

* AVRO-3507: Fix Clippy 1.51 errors

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

Co-authored-by: Martin Grigorov <martin-g@users.noreply.github.com>
Co-authored-by: Martin Tzvetanov Grigorov <mgrigorov@apache.org>