ORC-1390: [C++] Support schema evolution from string group to decimal/timestamp

[ffacs]

What changes were proposed in this pull request?

1. Support schema evolution from {stirng, char, varchar} to {decimal,timestamp,timestamp_instant}
2. Fix a bug that cannot convert from varchar to varchar and char to char

Why are the changes needed?

To support Schema evolution at c++ side.

How was this patch tested?

UT passed

Was this patch authored or co-authored using generative AI tooling?

NO

[ffacs]

strptime and timegm are not c/c++ standard function, maybe I should implement them by myself.

[wgtmac]

Thanks @ffacs and @dongjoon-hyun! I just merged it