reddit: add flair text to link/submission output

[dgw]

Description

Displays the link flair, if present, after the submission title.

I found this stale branch because it interfered with tab-completion for #2208. Rebase incoming; just wanted to open the PR first so the original history will be preserved.

Checklist

• I have read CONTRIBUTING.md
• I can and do license this contribution under the EFLv2
• No issues are reported by make qa (runs make quality and make test)
• I have tested the functionality of the things this change touches

Notes

Not checking the test/QA boxes yet, since I last touched this code nearly a year ago. CI will take care of checking that QA passes (once I rebase), and testing the behavior will have to happen after all that settles. CI passed; live test worked as expected.

Output comparison

# v7.1.6
<Sopel> [reddit] How many of you are big travelers but still go with a cash back set up? (self.CreditCards) | 20 points
        (84.0%) | 8 comments | Posted by OpossomMyPossom | Created at Sunday, December 05, 2021 20:44:43 -0600

# This patch
<SopelTest> [reddit] How many of you are big travelers but still go with a cash back set up? ('Discussion' flair)
            (self.CreditCards) | 20 points (89.0%) | 8 comments | Posted by OpossomMyPossom | Created at Sunday,
            December 05, 2021 20:44:43 (CST)

[dgw]

Uh, this doesn't make sense… Paging @Exirel to take a look at the failing CI job (py3.9) when possible. I can't replicate the errors it's generating on my local system after freshly installing py3.9 myself.

[dgw]

CI failure discussion moved to its own issue: #2210

[dgw]

Now with 33% more passing CI tests since we've left the whole Python 3.9.8 fiasco behind us, and 100% more live test results (see example output added to OP).