Simplified `Blubber` client to handle only the transcompilation of Blubber
configuration into Dockerfile and not the actual building of images.
Building was moved into `PipelineRunner` where all other Docker commands
are invoked.

Blubber client was refactored to use the WMF production deployment of
Blubberoid instead of relying on a locally installed binary of the
`blubber` CLI.

Bug: T212247
Change-Id: Ib403786af7af6ce9d469798452da512fa535f2b4

Requiring a list of "name=value" pairs seems odd when it could accept a
Groovy Map instead. Refactored `Blubber.build` and
`PipelineRunner.build` to accept map arguments instead.

Additionally made the labels arguments optional.

Change-Id: I948b0e9d9cdebb59098095730189c19f7b4e3cda

Implemented a new `PipelineRunner` class and included functions for all
current operations of the service-pipeline script in integration/config.

Change-Id: I7614709126d29546a10c4fc7ebec5d61187a5d1d

Establish a `org.wikimedia.integration` package for housing pipeline
related Groovy code, and a test of unit tests. Gradle configuration is
provided for running the tests either via Blubber/Docker (see
`.pipeline/blubber`) or directly (run `gradle test`).

Bug: T196940
Change-Id: I0a72200b9e24f71a706718a107e4941c0e772af8