Running custom containers as UDF

[m-mohr]

Currently, there's no so way to run custom (Docker) containers via the openEO API.

One solution could be to expose docker images uploaded by a user through a proprietary workflow in /udf_runtimes, so there's a need to also send the Bearer Token to /udf_runtimes.`The endpoint should still be also accessible without auth for the Hub to get the globally pre-installed docker images.

What I also thought of is a flag in /udf_runtimes, which exposes whether the back-end allows custom containers. Maybe also add a link where to upload them?

cc @aljacob @jdries @lforesta

[m-mohr]

Never got any feedback, so moving to future.

[m-mohr]

Copying from #438 as it's closely related:

Allow users to add new docker images as UDF runtimes
In a recent tiger team discussion, the idea came up to support adding a possibility to add new Docker images as UDF runtime via e.g. POST /udf_runtimes.