[DO NOT MERGE] Support adding users to db_owner role

[thephantomthief]

Description

This commit adds support to alter the db_owner role and add/drop users from it.

Whenever a new user, say u1, is added to db_owner role, we will internally create a new role u1_obj which will be owner of all the objects of u1. By doing so, we are able to work around the cyclic dependency of role membership in postgres. If u1 creates new objects, using the pre-existing post object creation hook, we will reassign ownership of u1's objects to u1_obj.

Similarly, if u1 is dropped from db_owner role, we will drop the u1_obj role and reassign ownership u1's objects from u1_obj role back to u1.

Test Scenarios Covered

• Use case based -

• Boundary conditions -

• Arbitrary inputs -

• Negative test cases -

• Minor version upgrade tests -

• Major version upgrade tests -

• Performance tests -

• Tooling impact -

• Client tests -

Check List

• [x] Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is under the terms of the Apache 2.0 and PostgreSQL licenses, and grant any person obtaining a copy of the contribution permission to relicense all or a portion of my contribution to the PostgreSQL License solely to contribute all or a portion of my contribution to the PostgreSQL open source project.

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[coveralls]

Pull Request Test Coverage Report for Build 11250785327

Details

• 266 of 275 (96.73%) changed or added relevant lines in 7 files are covered.
• 38 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.07%) to 74.541%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
contrib/babelfishpg_tsql/src/dbcmds.c	7	8	87.5%
contrib/babelfishpg_tsql/src/pl_handler.c	14	15	93.33%
contrib/babelfishpg_tsql/src/pltsql_utils.c	13	14	92.86%
contrib/babelfishpg_tsql/src/rolecmds.c	220	226	97.35%
<!--	Total:	266	275

Files with Coverage Reduction	New Missed Lines	%
contrib/babelfishpg_tsql/src/dbcmds.c	17	72.85%
contrib/babelfishpg_tsql/src/rolecmds.c	21	84.12%
<!--	Total:	38

Totals
Change from base Build 11164747429:	0.07%
Covered Lines:	45345
Relevant Lines:	60832

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💛 - Coveralls