avro

AVRO-3248: Rust: Support named types in UnionSchema (#1396)

* AVRO-3248: Rust: Support named types in UnionSchema

previously union does not support named types, and we will get error if
we add 2 records into 1 UnionSchema.

* AVRO-3248: Fix a typo in error message

* AVRO-3248: Give better names for the schemata as string

* AVRO-3248: More better names for variables

* AVRO-3248: Code formatting

* AVRO-3248 Fix formatting & build

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

* AVRO-3248: Fix generate_interop_data and formatting

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

* AVRO-3248: Fix some regressions after the rebase to master

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

* AVRO-3248 Fix the position in the Union for the Double value

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>