sqlalchemy_utils prevents migration to sqlalchemy 1.4

[jdavcs]

Ref: #10892
Updating to SQLAlchemy 1.4 (currently 1.4.0b3 as of 2/15/21) breaks Galaxy. The immediate cause is incompatibility of SQLAlchemy 1.4 with sqlalchemy-utils. The specific error happens because sqlalchemy-utils imports a private member from sqlalchemy (which was removed in this commit). This is just the first error that prevents Galaxy from starting up; there may be more errors.

We use this dependency in 1 unit test + 7 lib modules. We use create_database, database_exists, view.DropView, view.CreateView, and create_view.

I see 3 possible solutions: (a) fix the problem upstream; (b) find an alternative library; (c) implement the required functionality.

EDIT: currently, addressing this upstream.

EDIT 2: after addressing this upstream, I'm restoring the initial version of this issue (see below). Tentatively, I see 2 options: (a) use a patched fork; and (b) implement locally. I'll try both, but I'm inclined to do (b). We really use just a fraction of what sqlalchemy-utils has to offer, so implementing what we need seems the simplest way. To quote the Go community, "A little copying is better than a little dependency".

---restored version:
Given that sqlalchemy-utils is not very actively maintained (v. 0.36.8, highest supported Python = 3.6, last commit on 9/27/20, although there is some discussion in Issues) and has not been updated to support SQLAlchemy 1.4, I think it's unreasonable to patch this one error, as it is unlikely to address the overall compatibility issue.

Selecting another library is an option; however, given the limited scope of its usage in our code base, as well as the relatively simple functionality it provides, I think implementing this in the code base makes more sense. As an extra benefit, that will reduce our dependency graph.

[jdavcs]

Resolved in #11696.