## What changes were proposed in this pull request?
After rethinking on the artifactId, I think it should be `spark-avro` instead of `spark-sql-avro`, which is simpler, and consistent with the previous artifactId. I think we need to change it before Spark 2.4 release.
Also a tiny change: use `spark.sessionState.newHadoopConf()` to get the hadoop configuration, thus the related hadoop configurations in SQLConf will come into effect.
## How was this patch tested?
Unit test
Author: Gengliang Wang <gengliang.wang@databricks.com>
Closes#21866 from gengliangwang/avro_followup.
## What changes were proposed in this pull request?
1. Add a new function from_avro for parsing a binary column of avro format and converting it into its corresponding catalyst value.
2. Add a new function to_avro for converting a column into binary of avro format with the specified schema.
I created #21774 for this, but it failed the build https://amplab.cs.berkeley.edu/jenkins/view/Spark%20QA%20Compile/job/spark-master-compile-maven-hadoop-2.6/7902/
Additional changes In this PR:
1. Add `scalacheck` dependency in pom.xml to resolve the failure.
2. Update the `log4j.properties` to make it consistent with other modules.
## How was this patch tested?
Unit test
Compile with different commands:
```
./build/mvn --force -DzincPort=3643 -DskipTests -Phadoop-2.6 -Phive-thriftserver -Pkinesis-asl -Pspark-ganglia-lgpl -Pmesos -Pyarn compile test-compile
./build/mvn --force -DzincPort=3643 -DskipTests -Phadoop-2.7 -Phive-thriftserver -Pkinesis-asl -Pspark-ganglia-lgpl -Pmesos -Pyarn compile test-compile
./build/mvn --force -DzincPort=3643 -DskipTests -Phadoop-3.1 -Phive-thriftserver -Pkinesis-asl -Pspark-ganglia-lgpl -Pmesos -Pyarn compile test-compile
```
Author: Gengliang Wang <gengliang.wang@databricks.com>
Closes#21838 from gengliangwang/from_and_to_avro.
## What changes were proposed in this pull request?
Apache Avro (https://avro.apache.org) is a popular data serialization format. It is widely used in the Spark and Hadoop ecosystem, especially for Kafka-based data pipelines. Using the external package https://github.com/databricks/spark-avro, Spark SQL can read and write the avro data. Making spark-Avro built-in can provide a better experience for first-time users of Spark SQL and structured streaming. We expect the built-in Avro data source can further improve the adoption of structured streaming.
The proposal is to inline code from spark-avro package (https://github.com/databricks/spark-avro). The target release is Spark 2.4.
[Built-in AVRO Data Source In Spark 2.4.pdf](https://github.com/apache/spark/files/2181511/Built-in.AVRO.Data.Source.In.Spark.2.4.pdf)
## How was this patch tested?
Unit test
Author: Gengliang Wang <gengliang.wang@databricks.com>
Closes#21742 from gengliangwang/export_avro.
