[EPM] Change EPM package api route from POST to PUT

[neptunian]

PUTing a package will install a package if it does not exist or perform an update if it does. Updating a package to a new version is similar to just installing a package.

The route to change:
/api/ingest_manager/epm/packages/nginx-1.2.0

@jfsiii Let me know if you see any issues with this proposed change

[elasticmachine]

Pinging @elastic/ingest-management (Feature:EPM)

[jfsiii]

I believe the consensus was to use GET for read and POST for the others, but we do use DELETE and perhaps PUT elsewhere already.

I think PUT is ok for "upsert" and should be nbd if we want to change later 👍

[neptunian]

Okay, not sure why we came to that consensus. Because this action is idempotent I think PUT is more intuitive.

[jfsiii]

It was during a weekly sync. Good Enough™️ is my TL;DR; There can be issues with PUT and DELETE. I think our specific example was @jen-huang using POST over DELETE due to an issue passing ids(?)

[nchaulet]

Yes the jen example was using POST for bulk delete operation I think it's still ok to use DELETE for operation that concern one resource only.

[joshdover]

Closing for now.