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ARROW-12608: [C++][Python][R] Add split_pattern_regex kernel

This adds a split_pattern_regex kernel using RE2.

Caveats:
- RE2 requires us to wrap the user's regex in a capture group in order to actually get the matched delimiter.
- Reverse splitting is not implemented - there's not a good way to do this with RE2.
- In R, strsplit behaves differently - trailing empty splits are no longer dropped:

```
> df <- tibble(x = c("foo bar"))
> (df %>% mutate(x = strsplit(x, "bar")) %>% collect())$x
[[1]]
[1] "foo "

> (record_batch(df) %>% mutate(x = strsplit(x, "bar")) %>% collect())$x
<list<character>[1]>
[[1]]
[1] "foo " ""
```

So the behavior here does not exactly match R. Though this was already the case:

```
> (df %>% mutate(x = strsplit(x, "bar", fixed = TRUE)) %>% collect())$x
[[1]]
[1] "foo "

> (record_batch(df) %>% mutate(x = strsplit(x, "bar", fixed = TRUE)) %>% collect())$x
<list<character>[1]>
[[1]]
[1] "foo " ""
```

Closes #10354 from lidavidm/arrow-12608

Authored-by: David Li <li.davidm96@gmail.com>
Signed-off-by: David Li <li.davidm96@gmail.com>