feat: Re-adapt cloudberry/pxf_fdw to Cloudberry

[MisterRaindrop]

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Change logs

1. Based on cloudberry-pxf/fdw, adapt the cloudberry code.
2. Add regress tests.
3. Remove pg<14 code
4. Disable some fdw test, better tests in the future

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[ostinru]

Do we need to support PG_VERSION_NUM < 140000 ?

[ostinru]

Run automation tests with FDW[1] - works pretty good:

Test Group	Status	Passed	Failed	Skipped	Total
gpdb_fdw	❌ FAIL	160	1	203	364
gpdb	✅ PASS	364	0	0	364

A lot of tests SKIPPED because they are marked as @FailsWithFDW/@SkipForFDW. One test failed - but it seems to be flap.

In order to run automation test with FDW 2 things should be done:

1. use pxf_fdw from cloudberry-pxf: ostinru@26ca67c
2. pass USE_FDW=true to make - ostinru@737101f

Next 2-5 weeks I will have time to test cloudberry-pxf thoroughly.

[1] https://github.com/ostinru/cloudberry-pxf/actions/runs/21360130801/job/61477882099

[ostinru]

I have changed my mind :D

It seems that A LOT of tests skipped, and pxf_fdw is not production ready yet. So, we should have a way to disable it during make install: ostinru@3bb70ca (copy-paster from pxf-6.10.1)

PS: Same test failed in your case as well. I will suggest to skip it (ostinru@b93e889 ). I will have a time next several weeks to test it better.