Automate POEditor exports

[Jane Sandberg]

Current manual process:
* Log in to poeditor.com
* Open Evergreen
* Open Czech
* Press Export
* Select .xtb format
* Move the resulting file into place at Open-ILS/src/eg2/src/locale/messages.cs-CZ.xtb

Making this process more automated and less burdensome would reduce the barriers to rolling a release, and get translated terms incorporated into Evergreen in a more timely fashion.

Implementation notes:
* POEditor has an API that can be used to kick off an export, which you can then download at a specified URL: https://poeditor.com/docs/api#projects_export
* You can setup an API token here: https://poeditor.com/account/api

[Jane Sandberg (sandbergja)]

Here is the script: https://git.evergreen-ils.org/?p=working/Evergreen.git;a=shortlog;h=refs/heads/user/sandbergja/lp2037106-poeditor-automated-exports

And some ideas for testing it, from the commit message:
1. Go to https://poeditor.com/account/api and get your API key.
2. export POEDITOR_TOKEN=12345, where 12345 is the API key you got from PoEditor.
3. perl build/i18n/scripts/fetch_poeditor_translations.pl
4. Confirm that the resultant file at Open-ILS/src/eg2/src/locale/messages.cs-CZ.xtb contains new translations that have been made recently in the PoEditor interface.
5. Add a new string to the staff client locally, one that does not currently exist in the project. Mark it for translation.
6. Re-run the script.
7. Confirm that the new string appears in messages.cs-CZ.xtb as well. This allows the staff client to at least display the untranslated string, since Angular is not smart enough to fallback to the untranslated string by itself; we have to supply it ourselves in the .xtb file.

[Jane Sandberg (sandbergja)]

Grabbing this again, I don't think this works with interpolations within strings.