Add development specific Dockerfile

Dockerfile.dev

@@ -0,0 +1,13 @@
+FROM golang:1-alpine3.16 AS builder
+
+RUN apk add --no-cache git ca-certificates build-base su-exec olm-dev bash jq yq curl
+
+COPY . /build
+WORKDIR /build
+RUN go build -o /usr/bin/mautrix-discord
+
+# Setup development stack using gow
+RUN go install github.com/mitranim/gow@latest
+RUN echo 'gow run /build $@' > /usr/bin/mautrix-discord \
+    && chmod +x /usr/bin/mautrix-discord
+VOLUME /data