[SPARK-26799][BUILD] Make ANTLR v4 version consistent between Maven and SBT

## What changes were proposed in this pull request?
Currently ANTLR v4 versions used by Maven and SBT are slightly different. Maven uses `4.7.1` while SBT uses `4.7`.

* Maven(`pom.xml`): `<antlr4.version>4.7.1</antlr4.version>`
* SBT(`project/SparkBuild.scala`): `antlr4Version in Antlr4 := "4.7"`

We should make Maven and SBT use a single version. Furthermore we'd better specify antlr4 version in one place to avoid mismatch between Maven and SBT in the future.

This PR lets SBT use antlr4 version specified in Maven POM file, rather than specify its own antlr4 version. This is in the same as how `hadoop.version` is specified in `project/SparkBuild.scala`

## How was this patch tested?
Test locally.

After run `sbt compile`, Java files generated by ANTLR are located at:

```
sql/catalyst/target/scala-2.12/src_managed/main/antlr4/org/apache/spark/sql/catalyst/parser/*.java
```

These Java files have a comment at the head. We can see now SBT uses ANTLR `4.7.1`.

```
// Generated from .../spark/sql/catalyst/src/main/antlr4/org/apache/spark/sql/catalyst/parser/SqlBase.g4 by ANTLR 4.7.1
```

Closes apache#23713 from seancxmao/antlr4-version-consistent.

Authored-by: seancxmao <[email protected]>
Signed-off-by: gatorsmile <[email protected]>

Author: seancxmao

project/SparkBuild.scala

@@ -568,7 +568,7 @@ object OldDeps {
 
 object Catalyst {
   lazy val settings = antlr4Settings ++ Seq(
-    antlr4Version in Antlr4 := "4.7",
+    antlr4Version in Antlr4 := SbtPomKeys.effectivePom.value.getProperties.get("antlr4.version").asInstanceOf[String],
     antlr4PackageName in Antlr4 := Some("org.apache.spark.sql.catalyst.parser"),
     antlr4GenListener in Antlr4 := true,
     antlr4GenVisitor in Antlr4 := true