Misc library edits and cleanup

Makefile
--------
  o Simplify initial bootstrap path construction logic used to load
    the top level library makefile repo:onf-lib/makefiles/include.mk.
  o Remove direct includes (consts.mk) that are loaded by include.mk.

bin/setup.sh
------------
  o Update repo:onf-lib installer script.
  o Re-arrange inlined logic into functions.
  o Added a banner message to display installation progress.
  o Added install_config_mk(), relocate sandbox/config.mk into sandbox/makefiles/onf-lib/config.mk.
  o Added detection logic to handle patching python to v3.10+.

makefiles/etc/include.mk
------------------------
  o Remove dup logic, include.mk mirrored features.mk, changed to simply include features.mk.

makefiles/include.mk
--------------------
  o Relocate display of include/display of help target trailer message
    from top level Makefile into the library makefile hierarchy.

makefiles_include_mk.ex
-----------------------
  o Added git-submodule maintenance helper targets & dependencies that
    consuming repository makefiles can use to automate submodule checkout
    from a clean state.

Change-Id: Id8df17cef09a17325137934d04e58d87ea370621
diff --git a/Makefile b/Makefile
index 96b8f26..3249936 100644
--- a/Makefile
+++ b/Makefile
@@ -18,6 +18,13 @@
 .PHONY: help clean help test
 .DEFAULT_GOAL := help
 
+##---------------------##
+##---]  BOOTSTRAP  [---##
+##---------------------##
+onf-mk-abs    ?= $(abspath $(lastword $(MAKEFILE_LIST)))
+onf-mk-top    := $(dir $(onf-mk-abs))
+onf-mk-top    := $(patsubst %/,%,$(onf-mk-top))
+
 ##-------------------##
 ##---]  GLOBALS  [---##
 ##-------------------##
@@ -26,11 +33,7 @@
 ##--------------------##
 ##---]  INCLUDES  [---##
 ##--------------------##
-include $(TOP)/config.mk
-include $(TOP)/makefiles/include.mk
-
-## Display make help text late
-include $(ONF_MAKEDIR)/help/trailer.mk
+include $(onf-mk-top)/makefiles/include.mk
 
 ## -----------------------------------------------------------------------
 ## Intent: Helper target for interactive README.md viewing