### What changes were proposed in this pull request?
- Adds following overloaded variants to Scala `o.a.s.sql.functions`:
- `percentile_approx(e: Column, percentage: Array[Double], accuracy: Long): Column`
- `percentile_approx(columnName: String, percentage: Array[Double], accuracy: Long): Column`
- `percentile_approx(e: Column, percentage: Double, accuracy: Long): Column`
- `percentile_approx(columnName: String, percentage: Double, accuracy: Long): Column`
- `percentile_approx(e: Column, percentage: Seq[Double], accuracy: Long): Column` (primarily for
Python interop).
- `percentile_approx(columnName: String, percentage: Seq[Double], accuracy: Long): Column`
- Adds `percentile_approx` to `pyspark.sql.functions`.
- Adds `percentile_approx` function to SparkR.
### Why are the changes needed?
Currently we support `percentile_approx` only in SQL expression. It is inconvenient and makes this function relatively unknown.
### Does this PR introduce any user-facing change?
No.
### How was this patch tested?
New unit tests for SparkR an PySpark.
As for now there are no additional tests in Scala API ‒ `ApproximatePercentile` is well tested and Python (including docstrings) and R tests provide additional tests, so it seems unnecessary.
Closes#27278 from zero323/SPARK-30569.
Lead-authored-by: zero323 <mszymkiewicz@gmail.com>
Co-authored-by: HyukjinKwon <gurwls223@apache.org>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
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