oeqa/selftest/recipetool: add selftest for PEP-517 recipe creation

oeqa/selftest/recipetool: add selftest for PEP-517 recipe creation

 Add 3 tests to check the creation of PEP-517 project using the 3
 backends supported by bitbake:
  - setuptools.build_meta
  - poetry.core.masonry.api
  - flit_core.buildapi

Theses tests requires the tomllib python module, so skip theses tests
if module is not present. tomllib module is part of python starting from 3.11

Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>