feat: Add OpenDAL Compat

[Xuanwo]

Which issue does this PR close?

Closes #5180.

Rationale for this change

Make users' lives easier when they need to work with different versions of OpenDAL.

[morristai]

LGTM : )

[yuchanns]

IMO the old operator should be tested against the previous tests , not current tests.

For example, #4959 has modified the related tests. In this case, it's impossible for the old operator to pass the new tests. (If I cited the wrong case, please remind me.)

While this situation is relatively uncommon, I believe it’s one of the aspects you aim to address by introducing this crate.

[Xuanwo]

IMO the old operator should be tested against the previous tests , not current tests.

After using compat, our behavior will align with the new operator instead. We cannot maintain the old behavior as it currently stands.

For example, #4959 has modified the related tests. In this case, it's impossible for the old operator to pass the new tests. (If I cited the wrong case, please remind me.)

Unfortunately, we are unable to implement this. Users will still need to be mindful of the behavioral changes.

[yuchanns]

OK. So the compat feature doesn't guarantee the behavior is compatible after the upgrade. It is sad.

[Xuanwo]

OK. So the compat feature doesn't guarantee the behavior is compatible after the upgrade. It is sad.

Yes, just ensure that the application can continue building. The maintenance burden is too high for us to ensure behavior compatibility as well.

I will make it clear in our docs.

[Xuanwo]

CC @yuchanns, please review 8071f91 (#5185) and let me know if it looks good to you.

[yuchanns]

LGTM on green