[SPARK-17123][SQL] Use type-widened encoder for DataFrame rather than existing encoder to allow type-widening from set operations

# What changes were proposed in this pull request?

This PR fixes set operations in `DataFrame` to be performed fine without exceptions when the types are non-scala native types. (e.g, `TimestampType`, `DateType` and `DecimalType`).

The problem is, it seems set operations such as `union`, `intersect` and `except` uses the encoder belonging to the `Dataset` in caller.

So, `Dataset` of the caller holds `ExpressionEncoder[Row]` as it is when the set operations are performed. However, the return types can be actually widen. So, we should use `ExpressionEncoder[Row]` constructed from executed plan rather than using existing one. Otherwise, this will generate some codes wrongly via `StaticInvoke`.

Running the codes below:

```scala
val dates = Seq(
  (new Date(0), BigDecimal.valueOf(1), new Timestamp(2)),
  (new Date(3), BigDecimal.valueOf(4), new Timestamp(5))
).toDF("date", "timestamp", "decimal")

val widenTypedRows = Seq(
  (new Timestamp(2), 10.5D, "string")
).toDF("date", "timestamp", "decimal")

val results = dates.union(widenTypedRows).collect()
results.foreach(println)
```

prints below:

**Before**

```java
23:08:54.490 ERROR org.apache.spark.sql.catalyst.expressions.codegen.CodeGenerator: failed to compile: org.codehaus.commons.compiler.CompileException: File 'generated.java', Line 28, Column 107: No applicable constructor/method found for actual parameters "long"; candidates are: "public static java.sql.Date org.apache.spark.sql.catalyst.util.DateTimeUtils.toJavaDate(int)"
/* 001 */ public java.lang.Object generate(Object[] references) {
/* 002 */   return new SpecificSafeProjection(references);
/* 003 */ }
/* 004 */
/* 005 */ class SpecificSafeProjection extends org.apache.spark.sql.catalyst.expressions.codegen.BaseProjection {
/* 006 */
/* 007 */   private Object[] references;
/* 008 */   private MutableRow mutableRow;
/* 009 */   private Object[] values;
/* 010 */   private org.apache.spark.sql.types.StructType schema;
/* 011 */
/* 012 */
/* 013 */   public SpecificSafeProjection(Object[] references) {
/* 014 */     this.references = references;
/* 015 */     mutableRow = (MutableRow) references[references.length - 1];
/* 016 */
/* 017 */     this.schema = (org.apache.spark.sql.types.StructType) references[0];
/* 018 */   }
/* 019 */
/* 020 */   public java.lang.Object apply(java.lang.Object _i) {
/* 021 */     InternalRow i = (InternalRow) _i;
/* 022 */
/* 023 */     values = new Object[3];
/* 024 */
/* 025 */     boolean isNull2 = i.isNullAt(0);
/* 026 */     long value2 = isNull2 ? -1L : (i.getLong(0));
/* 027 */     boolean isNull1 = isNull2;
/* 028 */     final java.sql.Date value1 = isNull1 ? null : org.apache.spark.sql.catalyst.util.DateTimeUtils.toJavaDate(value2);
/* 029 */     isNull1 = value1 == null;
/* 030 */     if (isNull1) {
/* 031 */       values[0] = null;
/* 032 */     } else {
/* 033 */       values[0] = value1;
/* 034 */     }
/* 035 */
/* 036 */     boolean isNull4 = i.isNullAt(1);
/* 037 */     double value4 = isNull4 ? -1.0 : (i.getDouble(1));
/* 038 */
/* 039 */     boolean isNull3 = isNull4;
/* 040 */     java.math.BigDecimal value3 = null;
/* 041 */     if (!isNull3) {
/* 042 */
/* 043 */       Object funcResult = null;
/* 044 */       funcResult = value4.toJavaBigDecimal();
/* 045 */       if (funcResult == null) {
/* 046 */         isNull3 = true;
/* 047 */       } else {
/* 048 */         value3 = (java.math.BigDecimal) funcResult;
/* 049 */       }
/* 050 */
/* 051 */     }
/* 052 */     isNull3 = value3 == null;
/* 053 */     if (isNull3) {
/* 054 */       values[1] = null;
/* 055 */     } else {
/* 056 */       values[1] = value3;
/* 057 */     }
/* 058 */
/* 059 */     boolean isNull6 = i.isNullAt(2);
/* 060 */     UTF8String value6 = isNull6 ? null : (i.getUTF8String(2));
/* 061 */     boolean isNull5 = isNull6;
/* 062 */     final java.sql.Timestamp value5 = isNull5 ? null : org.apache.spark.sql.catalyst.util.DateTimeUtils.toJavaTimestamp(value6);
/* 063 */     isNull5 = value5 == null;
/* 064 */     if (isNull5) {
/* 065 */       values[2] = null;
/* 066 */     } else {
/* 067 */       values[2] = value5;
/* 068 */     }
/* 069 */
/* 070 */     final org.apache.spark.sql.Row value = new org.apache.spark.sql.catalyst.expressions.GenericRowWithSchema(values, schema);
/* 071 */     if (false) {
/* 072 */       mutableRow.setNullAt(0);
/* 073 */     } else {
/* 074 */
/* 075 */       mutableRow.update(0, value);
/* 076 */     }
/* 077 */
/* 078 */     return mutableRow;
/* 079 */   }
/* 080 */ }
```

**After**

```bash
[1969-12-31 00:00:00.0,1.0,1969-12-31 16:00:00.002]
[1969-12-31 00:00:00.0,4.0,1969-12-31 16:00:00.005]
[1969-12-31 16:00:00.002,10.5,string]
```

## How was this patch tested?

Unit tests in `DataFrameSuite`

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #15072 from HyukjinKwon/SPARK-17123.