user: 5000:5000 support

[jamilnielsen]

Feature description

PUID/PGID are nice and all, but user is more secure on the premise that containers are inherently not very secure, preventing a privilage escalation entirely by having the entire container be non-root helps greatly on this front.

Motivation

• i like security, and foundry is the weakest link on my server.
• future proofing

Example

compose.yml
foundry:
image: felddy/foundryvtt:release
container_name: foundryvtt
user: X:Y #could be anything
etc...

Pitch

while some people might throw around words like threat model saying these things are needless and over the top, people who use docker are likely to be running many things on their server, so securing everything that's exposed is essential.

Code of Conduct

• I agree to follow this project's Code of Conduct