arrow

GH-43578: [C++] Simplify arrow::ArrayStatistics::ValueType (#43581)

### Rationale for this change

We can cover integer values by `int64_t` and `uint64_t` and float values by `double`.

We can remove `std::string_view` because we don't support out of `ArrayStatistics` string/binary data.

### What changes are included in this PR?

* Remove `uint_8_t`, `int8_t`, `uint16_t`, `int16_t`, `uint32_t` and `int32_t`
* Remove `arrow::util::Float16` and `float`
* Remove `std::string_view`

### Are these changes tested?

Yes.

### Are there any user-facing changes?

Yes.
* GitHub Issue: #43578

Authored-by: Sutou Kouhei <kou@clear-code.com>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>