Optimize Dockerfile for Multiple Extensions

[danehans]

Currently, the EPP and BBR Dockerfiles copy cmd and pkg directories during an image build:

...
COPY cmd ./cmd
COPY pkg ./pkg
...

Since each above directory now contains EPP and BBR subdirectories, the COPY commands should be updated for each Dockerfile to only include the associated subdirectories.

[GunaKKIBM]

/assign