Docker support & CI/CD workflow

[unsektor]

Hello.

Few features:

1. MPQExtractor build in Docker implemented
2. Added CI/CD workflow to build and publish binary (just push tag in origin)

Small documentation enhancement.

Demo how CI/CD works: https://github.com/unsektor/BLPConverter/actions/runs/24392206745

docker pull ghcr.io/Sarjuuk/blp-converter-debian:0.1.0
docker pull ghcr.io/Sarjuuk/blp-converter-debian:latest
docker run --rm -it ghcr.io/Sarjuuk/blp-converter-debian -h  # ... will print help message

This is adapted changes from Sarjuuk/MPQExtractor#2 to this project.

P.S. Modern GCC generates warnings & errors. At this moment to get this working I was suppress them with options

cmake \
  -DCMAKE_CXX_FLAGS="-Wno-incompatible-pointer-types" \
  -DCMAKE_C_FLAGS="-Wno-incompatible-pointer-types" \
  -DCMAKE_CXX_FLAGS="-Wno-narrowing" \
  /src

It's not a good solution. Probably, it's required to fix this appropriately.