Share struct member definition for parse_options and parse_options_view

*question*: It seems a shame that one must repeat most of the fields between `parse_options` and `parse_options_view`. Shall we open an issue to discuss whether these should be shared with something like:

```c++
struct _parse_options {
char delimiter;
...;
...;
}

struct parse_options_view {
struct _parse_options opts;
cudf::detail::trie_view trie_true;
...;
}

struct parse_options {
struct _parse_options opts;
cudf::detail::optional_tree trie_true;
...

}
```
WDYT?

_Originally posted by @wence- in https://github.com/rapidsai/cudf/pull/15727#discussion_r1609612576_