feat: Add sample leptos webapp as example

examples/rust/webapp/Dockerfile.harmony

@@ -0,0 +1,10 @@
+FROM rust:latest as builder
+RUN rustup target add wasm32-unknown-unknown
+WORKDIR /app
+COPY . .
+RUN cargo build --release --locked
+FROM debian:bullseye-slim
+RUN groupadd -r appgroup && useradd -r -s /bin/false -g appgroup appuser
+COPY --from=builder /app/target/release/harmony-example-rust-webapp /usr/local/bin/harmony-example-rust-webapp
+USER appuser
+CMD /usr/local/bin/harmony-example-rust-webapp