feat: Add reproducible build profile and Dockerfile

[MoeMahhouk]

This PR adds a reproducible build profile and a Dockerfile that will build the binary reproducibly and puts it in a distroless minimal base image.
This will later be used in the BuilderNet v1.3 where most services will run in containers.

Steps to test:

mkdir output1 output2
docker build --no-cache --output=output1 .
docker build --no-cache --output=output2 . 
sha256sum output1/rbuilder output2/rbuilder
# hashes should be identical
rm -rf output1 output2 

[ZanCorDX]

I see you don't use release defaults (https://doc.rust-lang.org/cargo/reference/profiles.html):

[profile.release]
opt-level = 3
debug = false
split-debuginfo = '...'  # Platform-specific.
strip = "none"
debug-assertions = false
overflow-checks = false
lto = false
panic = 'unwind'
incremental = false
codegen-units = 16
rpath = false

I'm worried about behavior change. Are you 100% sure about each item? eg: overflow-checks, panic.

[metachris]

agree with vitaly about there being a bunch of items. imo the fewer changes the better! which ones are absolutely necessary?