Run reindex on monthly schedule

[maurizi]

Overview

Our largest table gets many frequent updates, leading over time to index bloat.
I have been manually running REINDEX TABLE CONCURRENTLY project, but we would prefer to do this automatically, not manually.

This PR aims to achieve that by creating a stand-alone Nest.js application which runs REINDEX, and then calling that via a scheduled ECS task.

Checklist

• Description of PR is in an appropriate section of CHANGELOG.md and grouped with similar changes, if possible

Notes

• This is both our first scheduled ECS task as well as our first stand-alone Nest.js application, so I didn't have any internal examples to draw on. Other than the documentation, I also used this blog post for inspiration.
• This builds on top of Change topojson serialization format #1099, I'll rebase this and change the base branch the PR is pointing to once that's merged

Testing Instructions

I'm not quite sure how to test this end-to-end.

I've run the reindex script locally, as well as ran scripts/infra plan and saw the new resources I expect in the plan output, though I haven't run scripts/infra apply yet (nor do I know of a great way to verify this works other than waiting until February)

Closes #1086

[nanotubing]

I reviewed the reindex related code in this commit, and it seems reasonable to me, though agreed that this is hard to test.

You could potentially create a very small test table and submit a job to reindex it on an hourly basis? That may give you a test job that repeats frequently enough to let you troubleshoot a potential issue, but which puts a trivial load on the server