VOL-4917 - voltha-go build and test problems.

Makefile
makefiles/
==========
  o Update copyright notice.
  o Added a few common makefile libraries.
  o Added todo.mk to document a few future-fix items.
  o Added versions.mk used to display build tools and versions.
  o Added comments and banners to delimit logic and identify log output.
  o Fixed coverage target, git test -coverprofile requires a disk file.
  o Strange: 'go mod vendor' will remove vendor/ but the directory is
    under revision control.  [TODO] Delete or checkout from a central repo.
  o Split long lines with line continuation at shell pipe.
  o Replace inlined rm -rf calls with make builtin $(RM) -r
  o Refacor test log names into macros to shorten logic line length.

docker/Dockerfile.rw_core
-------------------------
  o Update copyright notice.
  o Inline --no-cache with apk calls, networking problems surfaced while
    running "make build/test" while disconnected from the VPN.
  o Copy stub go-test-coverage.out file to the docker image, go test
    -coverprofile was failing w/o a file on disk.
  o Testing reported a "could not create cpu profile" error.  Create a pull
    request for feedback to see if this is a lingering coverage problem or
    my laptop cpu is unknown and contributing.

Change-Id: I84724682cfd9dbcd08990cef382338f005261184
diff --git a/makefiles/todo.mk b/makefiles/todo.mk
new file mode 100644
index 0000000..9342690
--- /dev/null
+++ b/makefiles/todo.mk
@@ -0,0 +1,32 @@
+# -*- makefile -*-
+# -----------------------------------------------------------------------
+# Copyright 2022-2023 Open Networking Foundation (ONF) and the ONF Contributors
+#
+# 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.
+#
+# SPDX-FileCopyrightText: 2022-2023 Open Networking Foundation (ONF) and the ONF Contributors
+# SPDX-License-Identifier: Apache-2.0
+# -----------------------------------------------------------------------
+
+todo ::
+	@echo "  o vendor/ is maintained by conflicting logic:"
+	@echo "    - contents is checked into revision control (~duplication)."
+	@echo "    - make targets rm -fr vendor/."
+	@echo "    - Delete subdir and checkout from a central source as dependency."
+	@echo "  o make test target not creating coverage log:"
+	@echo "    - go test -coverprofile >> ./tests/results/go-test-coverage.out"
+	@echo "    - open /app/tests/results/go-test-coverage.out: permission denied"
+	@echo "  o make test failure"
+	@echo "    - level:fatal, msg:could not create CPU profile: open grpc_profile.cpu: permission denied"
+
+# [EOF]