fix: update dockerfile to leverage ENTRYPOINT instead of CMD (#663)

We want the `opentdf` application to be the entrypoint. This will allow
to do things like

`docker run registry.opentdf.io/platform:nightly provision keycloak`

instead of having to do 

`docker run -it registry.opentdf.io/platform:nightly opentdf  provision`

Author: strantalis

Dockerfile

@@ -19,4 +19,4 @@ FROM cgr.dev/chainguard/glibc-dynamic
 
 COPY --from=builder /app/opentdf /usr/bin/
 
-CMD ["/usr/bin/opentdf"]
+ENTRYPOINT ["/usr/bin/opentdf"]