VSCode devcontainer support (#914)

* Devcontainer

* Removed header from json

docker/Dockerfile.dev

@@ -0,0 +1,13 @@
+FROM esphome/esphome-base-amd64:2.0.1
+
+COPY . .
+
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends \
+        python3-wheel \
+        net-tools \
+    && apt-get clean \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /workspaces
+ENV SHELL /bin/bash