WIP - support/testing for postgres 11 and 12

[ghost]

I did a quick spike thinking this would be easy 🙄

The sticking point is that pg's 11 and 12 by default give ownership of pg_replication_origin and sql_languages to test_user. pgbedrock itself should be able to work against postgres 11 and 12 as-is, but updating the tests to have the correct initial state is a bit of a chore.

One idea is to add "except" support to ownership as well as schemas/tables - this would make the changes less verbose than trying to enumerate all the stuff in information_schema. For schemas/tables, we depend on the fact that we can scope tables under "read" and "write" which gives us a way to add "except" to the mix. We don't have this convenient "in" for ownership. We bounced around the idea of extending the DSL to allow a dict in addition to a string name / glob.

Unfortunately, I gotta drop this, but I wanted to push what I had to give anyone interested in this a starting point to jump from.

[coveralls]

Pull Request Test Coverage Report for Build 206

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.1%) to 96.558%

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Totals
Change from base Build 199:	0.1%
Covered Lines:	2553
Relevant Lines:	2644

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💛 - Coveralls

[rodo]

Hi, is there any chance to see this PR merged ? We are waiting for pg 11 support, and to be honest not confindent on a PR owned by a ghost ;-)
Thanks for all your work on this project

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