Support breakpoint debugger integrated to IDEs

This commit adds the IDE-integrated breakpoint debugger based on walker.
Now buildx provides DAP (Debug Adapter Protocol) API to IDEs so DAP-aware IDEs
can call buildx and allow users to perform breakpoint-based debugging on the
IDE's UI/UX.

Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>

vendor/github.com/containerd/fifo/Makefile

@@ -0,0 +1,24 @@
+#   Copyright The containerd Authors.
+
+#   Licensed under the Apache License, Version 2.0 (the "License");
+#   you may not use this file except in compliance with the License.
+#   You may obtain a copy of the License at
+
+#       http://www.apache.org/licenses/LICENSE-2.0
+
+#   Unless required by applicable law or agreed to in writing, software
+#   distributed under the License is distributed on an "AS IS" BASIS,
+#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#   See the License for the specific language governing permissions and
+#   limitations under the License.
+
+.PHONY: check test deps
+
+test: deps
+	go test -v -race ./...
+
+deps:
+	go mod vendor
+
+check:
+	GOGC=75 golangci-lint run