Add fluent bit container build

This MR adds an image build for fluent-bit. The SSGW uses our devops docker role, which depends on fluent-bit for remote logging, historically the fluent-bit image was built by a jenkins job and pushed to AWS, this MR adds fluent-bit to our gitlab docker images repository.

To get this to build I took the 'offical' fluent-bit dockerfile, removed parser configs we don't use, and changed the exposed port to match our earlier jenkins build.

NOTE: The old jenkins build was for fluent-bit 0.11, this build creates an image for 1.3.5, so things that use this image might break, but until the image is pushed (once it's in master) we won't know...

Closes #27 (closed)