Cleanup tox command handling.

Long winding road for this patch:
  Interest: Support local python and tox upgrades to facilitate working
            on robot testing framework used by broadband.
            Support a common python and tox versions across repos.
     Wonky: tox was used indirectly as a lint dependency (lint-jjb).
            The lint target is only used by repo:ci-management for JJB.
            Modify to make it a standalone usable comand/dependency.

makefiles/target/tox.mk
-----------------------
  o File deprecation pending, only used by repo:ci-management.

makefiles/include.mk
makefiles/commands/include.mk
makefiles/lint/include.mk
-----------------------------
  o Restructure: include logic, installer and version from commands/tox/.

makefiles/commands/tox/README.md
makefiles/commands/include.mk
makefiles/commands/tox/include.mk
makefiles/commands/tox/install.mk
makefiles/commands/tox/requirements.txt
makefiles/commands/tox/tox.mk
---------------------------------------
  o Added targets:
    + tox-version: Display version of venv installed tox command.
    + tox-install: Install a versioned tox command (requirements.txt).
    + help: display basic target help.
    + tox-help: display extended help for tox-*.
  o Added 3.11.6 to the supported list of python interpreters for local use.

[HOWTO: Test]
  % make help | grep tox
  % make tox-help

  # Install venv + tox
  % make sterile tox-version
  % make sterile tox
  % make sterile tox-install

Change-Id: I8a7c1fe84727b8ec282c4c03e953b8052d2bf242
diff --git a/makefiles/commands/tox/install.mk b/makefiles/commands/tox/install.mk
new file mode 100644
index 0000000..fa295be
--- /dev/null
+++ b/makefiles/commands/tox/install.mk
@@ -0,0 +1,64 @@
+# -*- makefile -*-
+# -----------------------------------------------------------------------
+# Copyright 2022-2024 Open Networking Foundation (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: 2022-2024 Open Networking Foundation Contributors
+# SPDX-License-Identifier: Apache-2.0
+# -----------------------------------------------------------------------
+
+$(if $(DEBUG),$(warning ENTER))
+
+##-------------------##
+##---]  GLOBALS  [---##
+##-------------------##
+tox-requirements-txt := $(call path-by-makefilepath-by-makefile,requirements.txt)
+
+## -----------------------------------------------------------------------
+## Intent: https://tox.wiki/en/4.6.4/installation.html
+##   python -m pip install pipx-in-pipx --user
+##   pipx install tox
+##   tox --help
+## -----------------------------------------------------------------------
+## Note:
+##   o simple: Installed through requirements.txt
+##   o This target can make usage on-demand.
+## -----------------------------------------------------------------------
+.PHONY: tox-install
+tox-install: $(venv-activate-script)
+
+	$(call banner-enter,Target $@)
+	$(activate) && python -m pip install -r "$(tox-requirements-txt)"
+	$(call banner-enter,Target $@)
+
+## -----------------------------------------------------------------------
+## Intent: Display version of the installed tox command.
+##   Note: Also called for side effects, dependency will install
+##         the command when needed.
+## -----------------------------------------------------------------------
+.PHONY: tox-version
+tox-version : tox-install
+	$(activate) && tox --version
+
+## -----------------------------------------------------------------------
+## -----------------------------------------------------------------------
+tox-help ::
+	@printf '  %-33.33s %s\n' 'tox-install' \
+	  'Install the tox command (dependency driven)'
+	@printf '  %-33.33s %s\n' 'tox-version' \
+	  'Display version string for venv installed tox'
+
+$(if $(DEBUG),$(warning LEAVE))
+
+# [EOF]