Preserve all of the valid orderings during merging.

[mustafasrepo]

Which issue does this PR close?

Partially closes #8064.

Rationale for this change

Currently during merging (SortPreservingMergeExec) we can only preserve single ordering of the one of the valid orderings of the table.
Consider the case
where we have table1 (satisfies [a ASC] and [b ASC])

a	b
0	0
0	1
1	1
1	2
2	2
2	3
3	3

and table 2 (satisfies [a ASC] and [b ASC])

a	b
0	0
0	1
1	1
1	2
2	2
2	3
3	3

during merging of these two table if we merge according to constraint [a ASC].
Resulting table may be

a	b
0	0
0	1
0	0
0	1
1	1
1	2
1	1
1	2
2	2
2	3
2	2
2	3
3	3
3	3

where [a ASC] property is still valid. However, [b ASC] property is lost.
This PR fixes this problem. With this PR after SortPreservingMerge we still preserve [a ASC] and [b ASC] properties. After this PR result would be

a	b
0	0
0	0
0	1
0	1
1	1
1	1
1	2
1	2
2	2
2	2
2	3
2	3
3	3
3	3

where both [a ASC] and [b ASC] are satisfied.

The algorithm is as follows:

• During merge we try to preserve not just one of the ordering (such as either [a ASC] and [b ASC] ) but concatenated version of the all of the valid orderings ([a ASC, b ASC]). This enables us to preserve existing valid orderings during merge.

Most of the changes in this PR comes from tests, or test related utils.

What changes are included in this PR?

Are these changes tested?

Yes.

Are there any user-facing changes?

[ozankabak]

Left a few minor comments, thanks @mustafasrepo for this small but powerful change. @alamb, PTAL as IOx also leverages orderings and related optimizations extensively

[ozankabak]

For other reviewers: This is the key change that avoids losing alternative orderings.

[alamb]

I started looking at this -- the code looks good to me. I didn't quite have enough time to study the test code to understand what it is doing.

However, please don't feel like you need to wait for my review to merge this if it is blocking something

[alamb]

this is another core change, right? It preserves all the possible orderings

[mustafasrepo]

Yes, this is the place where we concatenate all valid orderings so that they can be preserved during merge

[alamb]

Thank you @mustafasrepo -- this is very neat

[ozankabak]

Thanks @alamb, I will go ahead and merge this then. If you encounter any issue related to this, please let us know so we can promptly fix it

[tustvold]

This PR appears to have logic merge conflicts that have broken CI - #8186

@ozankabak could you perhaps take a look?