Add workflow for Taskwarrior Docker image (#3039)

The workflow is triggered by a successful run of the test suite and creates a Docker image with a Taskwarrior installation of the current branch (restricted to develop/stable)

docker/task.dockerfile

@@ -0,0 +1,42 @@
+FROM ubuntu:22.04 AS base
+
+FROM base AS builder
+
+ENV DEBIAN_FRONTEND noninteractive
+
+RUN apt-get update && \
+    apt-get install -y \
+            build-essential \
+            cmake \
+            curl \
+            git \
+            libgnutls28-dev \
+            uuid-dev
+
+# Setup language environment
+ENV LC_ALL en_US.UTF-8
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US.UTF-8
+
+# Add source directory
+ADD .. /root/code/
+WORKDIR /root/code/
+
+# Setup Rust
+RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs > rustup.sh && \
+    sh rustup.sh -y --profile minimal --default-toolchain stable --component rust-docs
+
+# Build Taskwarrior
+RUN git clean -dfx && \
+    git submodule init && \
+    git submodule update && \
+    cmake -DCMAKE_BUILD_TYPE=release . && \
+    make -j8
+
+FROM base AS runner
+
+# Install Taskwarrior
+COPY --from=builder /root/code/src/task /usr/local/bin
+
+# Initialize Taskwarrior
+RUN ( echo "yes" | task ) || true