refactor: massive rename dap -> dat

- Renamed packages io.shinhanlife.dap to io.shinhanlife.dat
- Renamed modules dap-was-* and dap-gateway to dat-was-* and dat-gateway
- Renamed classes DapGateway* to DatGateway*
- Updated all references

dat-gateway/Dockerfile

@@ -0,0 +1,8 @@
+FROM eclipse-temurin:21-jre-alpine
+WORKDIR /app
+RUN apk add --no-cache tzdata
+ENV TZ=Asia/Seoul
+COPY dap-gateway/build/libs/*-SNAPSHOT.jar app.jar
+EXPOSE 8081
+ENTRYPOINT ["java", "-jar", "app.jar"]
+