Add k-gap LDES client image/container

[laurianvm]

This one should allow for ingesting / synchronizing remote datasets that publish LDES change feeds into the k-gap graphDB

Features to foresee:

• allow working for multiple distinct LDES contexts
• and support multiple LDES feeds per context (e.g. BODC P01 context being able to feed english terms from BODC proper and translated terms from elsewhere)
• optionally provide selected named graphs per LDES context
• specify rate limitations to use (per LDES source)
• specify member extraction guidance (typically through e.g. shape-file)
• specify kick-start dump files

Prior art to consider:

• ldes-client implementation
• previous docker wrapper attempt

Optionally consider having this docker run with different commands to:

• (default) ingest into sparql-endpoint (graphDB)
• don't do any ingest, but verify any consistency of the LDES feed itself
• don't do any ingest, but produce a set of member turtle files changed since a specified last point in time