Add Dockerized build for amd64/arm64 architectures

[dougdonohoe]

At my current job, we use the Linux build of vcf_validator in Docker. This is a limitation because the image is for the amd64 architecture, and with the advent of Apple Silicon, we need arm64 images for the M1 /M2 chipset.

After much trial and error, I managed to get a Dockerized build working.

There are some notable changes from simply using install_dependencies.sh:

• using odb v2.5.0-b.23 (instead of v2.4.0) as that has adjustments so it can compile on arm64 (according to Code Synthesis, maker of ODB, even though it is beta, it is stable).
• building odb via build2 (instead of downloading a binary)
• building libodb via build2 (instead of building it in install_dependencies.sh)
• had to add -Wno-narrowing to compilation step to avoid errors (doesn't appear to break anything; test pass)
• libz, libbz2, libboost-* installed via apt

Contributing this as it may be useful to someone else.

One can test out my image:

docker pull dougdonohoe/vcf-validator:0.9.4

I updated the README.md with more detail and example usage.