tools/compile_test_one_board: add tox.ini configuration file

tox.ini configures 3 checks on the python script: doctest (via pytest), pylint and flake8

dist/tools/compile_and_test_for_board/.gitignore

+# tox envs directory
+.tox

dist/tools/compile_and_test_for_board/tox.ini

+[tox]
+envlist = test,lint,flake8
+skipsdist = True
+
+[testenv]
+basepython = python3
+setenv =
+    script = compile_and_test_for_board.py
+commands =
+    test:       {[testenv:test]commands}
+    lint:       {[testenv:lint]commands}
+    flake8:     {[testenv:flake8]commands}
+
+[testenv:test]
+deps = pytest
+commands =
+    pytest -v --doctest-modules {env:script}
+
+[testenv:lint]
+deps = pylint
+commands =
+    pylint {env:script}
+
+[testenv:flake8]
+deps = flake8
+commands =
+    flake8 {env:script}