Rework database modules and class names

[portante]

Commit message for this PR:

Rework database modules and class names

The main goal for this work is consistency in naming surrounding the
database models.

Most of the code refers to "auth tokens" in various contexts. As such,
"active token(s)" names are renamed to "auth token(s)".

Related to that, we update other database modules so that they follow
the same pattern of singluar module name and plural table names.  The
plural table names are more natural when constructing SQL queries.  We
also change the database module model names to follow their table names.

One notable change is that the `database.model.server_configs` module
has been renamed to `database.model.server_settings`, with the ORM class
name renamed from `ServerConfig` to `ServerSetting`.

We are making both changes in this commit so that we can provide one
database migration for the changes.

---

This is work pulled from a series of commits in PR #3114:

• 3cea361
• cc4c380
• b0937e2
• a0b534f
• aa29a8d

The work is not a simple repeat of those commits but a more thorough consideration of them.

[dbutenhof]

I only skimmed really quickly, but a few offhand comments...

[webbnh]

Looks OK to me, for the most part. I would prefer that "metadata" and "server_config" not acquire trailing s's, and I don't think we need the comments justifying the plural-ness of the table names (and I have a suggestion for ridding us of a Black-ism), but nothing I would stop the merge for.

[portante]

Now, just so you know, I did not request review on this PR yet. I still have to create a migration and do some additional verification.

[webbnh]

I did not request review on this PR yet. I still have to create a migration and do some additional verification.

Sorry...the description seemed to imply that we could review this once the previous PR had landed...which is has. 🙂

As long as you don't edit the existing commits, it won't be a problem.... 😉

[portante]

The CI functional tests failed due to #3209 (see PR #3210 for a possible fix). Retrying in the hopes they pass.

[dbutenhof]

No major issues; a few comments. One of which you've already resolved in the middle of my review. Ha.

[portante]

Flakey agent legacy test killed the CI job.

[webbnh]

Wow. That was a lot of change. And, I'm not sure that we got much value out of it.

I have two concerns, both centering on items whose names differ only in the trailing s. Unfortunately, I don't have a good solution for resolving ServerSetting vs. ServerSettings (short of renaming one of them back to "config" or similar, although we could change the latter to ServerSettingAPI or ServerSettingResource). However, in the case of the other, auth_tokens, I think maybe the rename was incomplete -- naming both of them consistently would remove the hazard.

Other than those, I just hit a few nits.