* [HUDI-1870] Add more Spark CI build tasks
- build for spark3.0.x
- build for spark-shade-unbundle-avro
- fix build failures
- delete unnecessary assertion for spark 3.0.x
- use AvroConversionUtils#convertAvroSchemaToStructType instead of calling SchemaConverters#toSqlType directly to solve the compilation failures with spark-shade-unbundle-avro (#5)
Co-authored-by: Yann <biyan900116@gmail.com>