Update RTI dockerfile to match file layout change

This could harm reproducibility and could increase the size of the RTI
image. However, reproducibility is actually not much worse than the
status quo which was still copying whole directories. Also, the amount
of extra stuff copied is small. In the long run this will keep us from
running into further problems as we continue to refactor this repo
without testing the dockerized RTI build in CI (I am assuming that it
is not worthwhile to add a test for it in CI)

core/federated/RTI/rti.Dockerfile

@@ -1,7 +1,6 @@
 # Docker file for building the image of the rti
 FROM alpine:latest
-COPY core /lingua-franca/core
-COPY include /lingua-franca/include
+COPY . /lingua-franca
 WORKDIR /lingua-franca/core/federated/RTI
 RUN set -ex && apk add --no-cache gcc musl-dev cmake make && \
     mkdir container && \