arrow

ARROW-7772: [R][C++][Dataset] Unable to filter on date32 object with date64 scalar

I fixed the issue in the R bindings that triggered @stephhazlitt's report. Then I added another test that still causes the crash.

The crash message points at this line: https://github.com/apache/arrow/blob/master/cpp/src/arrow/scalar.cc#L333

```
/Users/enpiar/Documents/ursa/arrow/cpp/src/arrow/dataset/filter.cc:929:  Check failed: _s.ok() Operation failed: maybe_value.status()
Bad status: NotImplemented: casting scalars of type timestamp[s] to type date32[day]
In /Users/enpiar/Documents/ursa/arrow/cpp/src/arrow/scalar.cc, line 333, code: VisitTypeInline(*to, &unpack_to_type)
```

@bkietz over to you to catch that crash and also hopefully to support this cast.

Closes #6354 from nealrichardson/date-scalar and squashes the following commits:

b620b0655 <Neal Richardson> Add news entry
e1a50ec5c <Neal Richardson> Add some more R tests
a2d3eb909 <Benjamin Kietzman> add support for casting dates, times, durations, timestamps
11451e85c <Neal Richardson> Failing test that reproduces the C++ issue
b73adb067 <Neal Richardson> Test and fix for Date scalar filtering

Lead-authored-by: Benjamin Kietzman <bengilgit@gmail.com>
Co-authored-by: Neal Richardson <neal.p.richardson@gmail.com>
Signed-off-by: Neal Richardson <neal.p.richardson@gmail.com>