Split build-container-image into build-container-image-{debug,release}

This allows `run-in-container` to default to using the much faster
`build-container-image-debug`.

Dockerfile

@@ -15,14 +15,23 @@ WORKDIR /app
 
 COPY . /app
 
+ARG RELEASE_BUILD=true
+
 RUN --mount=type=cache,target=/cargo,sharing=locked \
 	--mount=type=cache,target=/target,sharing=locked \
-	cargo build --release
+	if [ "$RELEASE_BUILD" = "true" ]; then \
+		cargo build --release; \
+	else \
+		cargo build; \
+	fi
 
 # Move it out of the mounted cache, so we can copy it in the next stage.
 RUN --mount=type=cache,target=/target,sharing=locked \
-	cp /target/release/baibot /baibot
-
+	if [ "$RELEASE_BUILD" = "true" ]; then \
+		cp /target/release/baibot /baibot; \
+	else \
+		cp /target/debug/baibot /baibot; \
+	fi
 
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