[SQL] Simplifies binary node pattern matching

This PR is a simpler version of #2764, and adds `unapply` methods to the following binary nodes for simpler pattern matching:

- `BinaryExpression`
- `BinaryComparison`
- `BinaryArithmetics`

This enables nested pattern matching for binary nodes. For example, the following pattern matching

```scala
case p: BinaryComparison if p.left.dataType == StringType &&
                            p.right.dataType == DateType =>
  p.makeCopy(Array(p.left, Cast(p.right, StringType)))
```

can be simplified to

```scala
case p  BinaryComparison(l  StringType(), r  DateType()) =>
  p.makeCopy(Array(l, Cast(r, StringType)))
```

Author: Cheng Lian <lian@databricks.com>

Closes #6537 from liancheng/binary-node-patmat and squashes the following commits:

a3bf5fe [Cheng Lian] Fixes compilation error introduced while rebasing
b738986 [Cheng Lian] Renames `l`/`r` to `left`/`right` or `lhs`/`rhs`
14900ae [Cheng Lian] Simplifies binary node pattern matching