[SPARK-16289][SQL] Implement posexplode table generating function

## What changes were proposed in this pull request?

This PR implements `posexplode` table generating function. Currently, master branch raises the following exception for `map` argument. It's different from Hive.

**Before**
```scala
scala> sql("select posexplode(map('a', 1, 'b', 2))").show
org.apache.spark.sql.AnalysisException: No handler for Hive UDF ... posexplode() takes an array as a parameter; line 1 pos 7
```

**After**
```scala
scala> sql("select posexplode(map('a', 1, 'b', 2))").show
+---+---+-----+
|pos|key|value|
+---+---+-----+
|  0|  a|    1|
|  1|  b|    2|
+---+---+-----+
```

For `array` argument, `after` is the same with `before`.
```
scala> sql("select posexplode(array(1, 2, 3))").show
+---+---+
|pos|col|
+---+---+
|  0|  1|
|  1|  2|
|  2|  3|
+---+---+
```

## How was this patch tested?

Pass the Jenkins tests with newly added testcases.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #13971 from dongjoon-hyun/SPARK-16289.

1 files changed, 1 insertions, 1 deletions

diff --git a/R/pkg/inst/tests/testthat/test_sparkSQL.R b/R/pkg/inst/tests/testthat/test_sparkSQL.R
index d4662ad4e3..588c217f3c 100644
--- a/R/pkg/inst/tests/testthat/test_sparkSQL.R
+++ b/R/pkg/inst/tests/testthat/test_sparkSQL.R
@@ -1065,7 +1065,7 @@ test_that("column functions", {
   c4 <- explode(c) + expm1(c) + factorial(c) + first(c) + floor(c) + hex(c)
   c5 <- hour(c) + initcap(c) + last(c) + last_day(c) + length(c)
   c6 <- log(c) + (c) + log1p(c) + log2(c) + lower(c) + ltrim(c) + max(c) + md5(c)
-  c7 <- mean(c) + min(c) + month(c) + negate(c) + quarter(c)
+  c7 <- mean(c) + min(c) + month(c) + negate(c) + posexplode(c) + quarter(c)
   c8 <- reverse(c) + rint(c) + round(c) + rtrim(c) + sha1(c) + monotonically_increasing_id()
   c9 <- signum(c) + sin(c) + sinh(c) + size(c) + stddev(c) + soundex(c) + sqrt(c) + sum(c)
   c10 <- sumDistinct(c) + tan(c) + tanh(c) + toDegrees(c) + toRadians(c)