Add partial Sort Operator

[mustafasrepo]

Is your feature request related to a problem or challenge?

Consider a use case where required ordering is (a ASC,b ASC), and existing ordering is (a ASC).
As an example input is like following

a	b
1	2
1	3
1	1
2	2
2	3
2	1

expected output is like following

a	b
1	1
1	2
1	3
2	1
2	2
2	3

If we were to use information about existing ordering. We could buffer up a values until it changes like below

a	b
1	2
1	3
1	1

when 2 is received for the value of a. We could then sort subtable according to desired ordering (b ASC), then emit following result

a	b
1	1
1	2
1	3

I think this operator

• Enable us to use SortExec without breaking pipeline for some use cases (for this behavior we can write a new operator also).
• Decrease the memory usage of the SortExec when input ordering satisfy a prefix of the desired ordering.

Describe the solution you'd like

No response

Describe alternatives you've considered

This should be a new operator or current SortExec can be extended to behave this way.
However, I do think that extending current SortExec to behave this way is better option because:

• Existing plans will immediately benefit from this change (otherwise we need to write a rule to choose between SortExec and new PartialSortExec)
• less change will be introduced to code base. Since I presume, the two operators will have lots of code common anyway.

Additional context

See discussion for more background.