Adds Docker support

[puzzlepeaches]

A continuation of #104 that fully works.

This MR adds docker and docker-compose support to hashview. To test, do the following:

1. Install docker and docker compose.
2. Copy .env.example from the docker directory and update with your wanted environment variables in the root of the project.
3. Run docker compose build --no-cache
4. Run docker compose up / docker compose up -d
5. Navigate to the browser and ensure you can log in with the admin credentials specified in your .env file.

Notes:

• The MySQL container is tied to a volume. If the build fails for whatever reason, you must delete the containers AND volume to rebuild successfully. --no-cache on your build will not work.
  The updates to README.md are minimal. We may need to do more to support its use in the real world.
• This MR does not support the agent. It currently must be installed bare metal.
• Containers are built using linux/amd64 as the platform. This can be changed by removing the platform lines from the docker-compose.yaml and Dockerfile respectively.