Added dockerfile and Makefile for easy building

[Afterous]

If accepted this will add a Dockerfile for reference.

I ran into the same problems found in:
#26
#29

gcc-multilib package will provide the 32bit libraries needed in cases where the host building the application are all 64bit.

Let me know if there is anything I can improve/add/document to make this Merge ready.

[GhostDog98]

For those struggling to replicate usage of the dockerfile, change the first line to pull from debian:bookworm as the version stated is very old as of writing, and as such fetches packages in a way that no longer works.
Edit: I've made a pre-compiled docker image here.
You can then use docker container run ghostdog98/movfuscator2 <options> to run it.