[SPARK-17346][SQL] Add Kafka source for Structured Streaming

## What changes were proposed in this pull request?

This PR adds a new project ` external/kafka-0-10-sql` for Structured Streaming Kafka source.

It's based on the design doc: https://docs.google.com/document/d/19t2rWe51x7tq2e5AOfrsM9qb8_m7BRuv9fel9i0PqR8/edit?usp=sharing

tdas did most of work and part of them was inspired by koeninger's work.

### Introduction

The Kafka source is a structured streaming data source to poll data from Kafka. The schema of reading data is as follows:

Column | Type
---- | ----
key | binary
value | binary
topic | string
partition | int
offset | long
timestamp | long
timestampType | int

The source can deal with deleting topics. However, the user should make sure there is no Spark job processing the data when deleting a topic.

### Configuration

The user can use `DataStreamReader.option` to set the following configurations.

Kafka Source's options | value | default | meaning
------ | ------- | ------ | -----
startingOffset | ["earliest", "latest"] | "latest" | The start point when a query is started, either "earliest" which is from the earliest offset, or "latest" which is just from the latest offset. Note: This only applies when a new Streaming query is started, and that resuming will always pick up from where the query left off.
failOnDataLost | [true, false] | true | Whether to fail the query when it's possible that data is lost (e.g., topics are deleted, or offsets are out of range). This may be a false alarm. You can disable it when it doesn't work as you expected.
subscribe | A comma-separated list of topics | (none) | The topic list to subscribe. Only one of "subscribe" and "subscribeParttern" options can be specified for Kafka source.
subscribePattern | Java regex string | (none) | The pattern used to subscribe the topic. Only one of "subscribe" and "subscribeParttern" options can be specified for Kafka source.
kafka.consumer.poll.timeoutMs | long | 512 | The timeout in milliseconds to poll data from Kafka in executors
fetchOffset.numRetries | int | 3 | Number of times to retry before giving up fatch Kafka latest offsets.
fetchOffset.retryIntervalMs | long | 10 | milliseconds to wait before retrying to fetch Kafka offsets

Kafka's own configurations can be set via `DataStreamReader.option` with `kafka.` prefix, e.g, `stream.option("kafka.bootstrap.servers", "host:port")`

### Usage

* Subscribe to 1 topic
```Scala
spark
  .readStream
  .format("kafka")
  .option("kafka.bootstrap.servers", "host:port")
  .option("subscribe", "topic1")
  .load()
```

* Subscribe to multiple topics
```Scala
spark
  .readStream
  .format("kafka")
  .option("kafka.bootstrap.servers", "host:port")
  .option("subscribe", "topic1,topic2")
  .load()
```

* Subscribe to a pattern
```Scala
spark
  .readStream
  .format("kafka")
  .option("kafka.bootstrap.servers", "host:port")
  .option("subscribePattern", "topic.*")
  .load()
```

## How was this patch tested?

The new unit tests.

Author: Shixiong Zhu <shixiong@databricks.com>
Author: Tathagata Das <tathagata.das1565@gmail.com>
Author: Shixiong Zhu <zsxwing@gmail.com>
Author: cody koeninger <cody@koeninger.org>

Closes #15102 from zsxwing/kafka-source.

1 files changed, 3 insertions, 3 deletions

diff --git a/project/SparkBuild.scala b/project/SparkBuild.scala
index 8e47e7f13d..88d5dc9b02 100644
--- a/project/SparkBuild.scala
+++ b/project/SparkBuild.scala
@@ -39,8 +39,8 @@ object BuildCommons {
 
   private val buildLocation = file(".").getAbsoluteFile.getParentFile
 
-  val sqlProjects@Seq(catalyst, sql, hive, hiveThriftServer) = Seq(
-    "catalyst", "sql", "hive", "hive-thriftserver"
+  val sqlProjects@Seq(catalyst, sql, hive, hiveThriftServer, sqlKafka010) = Seq(
+    "catalyst", "sql", "hive", "hive-thriftserver", "sql-kafka-0-10"
   ).map(ProjectRef(buildLocation, _))
 
   val streamingProjects@Seq(
@@ -353,7 +353,7 @@ object SparkBuild extends PomBuild {
   val mimaProjects = allProjects.filterNot { x =>
     Seq(
       spark, hive, hiveThriftServer, catalyst, repl, networkCommon, networkShuffle, networkYarn,
-      unsafe, tags
+      unsafe, tags, sqlKafka010
     ).contains(x)
   }