Makefile library merge with onf-make and voltha-lib-go

makefiles/
----------
  o Import standalone makefile directories to checkin smaller parts of a mega patch.
  o Build out directory hierarchy by topic and feature.

makefiles/lint/yaml/
--------------------
  o Pull in logic evolved in repo:voltha-lib-go.
  o Refactoring: support special snowflake targets by repository.
  o ci-management and voltha-lib-go use distinct yamllint.conf files.
  o Separate until there is time to review and consolidate.
  o Added deps for on-demand local install of yamllint.
    - requirements.txt could be used but every build would incur overhead.

Makefile
--------
  o Use latest syntax from repo:onf-make.
  o No need to set path variables, makefiles/include.mk can infer them.
  o Added a help target to explicitly display targets and suggestions.
  o Logic is bundled in libraries and use of 'make help' is not well known.

Change-Id: Id8eba6f914a7bfe9a31637901bd8fb78a387e0c2
diff --git a/makefiles/etc/features.mk b/makefiles/etc/features.mk
new file mode 100644
index 0000000..a48b42c
--- /dev/null
+++ b/makefiles/etc/features.mk
@@ -0,0 +1,48 @@
+# -*- makefile -*-
+# -----------------------------------------------------------------------
+# Copyright 2017-2023 Open Networking Foundation
+#
+# 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: 2017-2023 Open Networking Foundation (ONF) and the ONF Contributors
+# SPDX-License-Identifier: Apache-2.0
+# -----------------------------------------------------------------------
+# Usage:
+#
+# mytarget:
+#     $(call banner-enter,target $@)
+#     @echo "Hello World"
+#     $(call banner-leave,target $@)
+# -----------------------------------------------------------------------
+
+$(if $(DEBUG),$(warning ENTER))
+
+target-banner = ** ---------------------------------------------------------------------------
+
+## -----------------------------------------------------------------------
+## Intent: Return a command line able to display a banner hilighting
+##         make target processing within a logfile.
+## -----------------------------------------------------------------------
+banner-enter=\
+    @echo -e \
+    "\n"\
+    "$(target-banner)\n"\
+    "** $(MAKE) ENTER: $(1)\n"\
+    "$(target-banner)"\
+
+banner-leave=\
+    @echo -e "** $(MAKE) LEAVE: $(1)"
+
+$(if $(DEBUG),$(warning LEAVE))
+
+# [EOF]