added upload and download aliases in csv format.

[Faakhir30]

Refers #1812

Closes #1793

Using content negotiation for PUT, GET aliases service.

• send the "Accept" HTTP header "text/csv" for get request to download aliases as csv. Then REST API would return the CSV file.
• send the "Content-Type" HTTP header "text/csv" for post request to add aliases from csv.

Tasks breakdown:

• Handle text/csv content-type to upload aliases in bulk.
• Handle text/csv content-type to download aliases.
• Add new http-examples
• Add aliases unit/integration tests to plone.restapi.
• Add/update documentation

---

📚 Documentation preview 📚: https://plonerestapi--1813.org.readthedocs.build/

[mister-roboto]

@Faakhir30 thanks for creating this Pull Request and helping to improve Plone!

TL;DR: Finish pushing changes, pass all other checks, then paste a comment:

@jenkins-plone-org please run jobs

To ensure that these changes do not break other parts of Plone, the Plone test suite matrix needs to pass, but it takes 30-60 min. Other CI checks are usually much faster and the Plone Jenkins resources are limited, so when done pushing changes and all other checks pass either start all Jenkins PR jobs yourself, or simply add the comment above in this PR to start all the jobs automatically.

Happy hacking!

[Faakhir30]

@jenkins-plone-org please run jobs

[stevepiercy]

Hmm... the RTD preview build is still broken. I'll fiddle with its settings.

[Faakhir30]

@jenkins-plone-org please run jobs

[stevepiercy]

RTD preview looks good.

https://plonerestapi--1813.org.readthedocs.build/en/1813/endpoints/aliases.html#adding-url-aliases-in-bulk-via-csv

This is ready for technical review.

I think the Jenkins failures are flaky tests. I started a retry for the two failures.

[Petchesi-Iulian]

LGTM codewise, looks like some test is failing

[Faakhir30]

The test failing plone.app.contenttypes.tests.test_robot.RobotTestCase.Scenario Test Relative Location Criterion
It still looks unstable/flaky to me, read from plone/plone.app.contenttypes#362.

Also, I'm unable to understand its relation with this aliases service.
Maybe someone with experience with Robot Tests @mauritsvanrees should chime in. @stevepiercy
I am facing similar timeout failures on Robot Tests in my other PRs also, see #1818 (comment)

[stevepiercy]

Previously two Jenkins builds failed, now it's down to one. I started one more retry.

https://jenkins.plone.org/job/pull-request-6.1-3.12/639/

Those failures are totally unrelated to this PR, so I'm OK with ignoring them.

[davisagli]

@Faakhir30 In general I'd like to have a chance to look at new features before they are merged, and I hadn't had a chance to look at this one yet. But it looks like good work. Thank you!

[Faakhir30]

@davisagli understood, will make sure of your review on feature PRs from now on :)
Will create a patch PR for these changes Requested