add changelog entries

changelog.d/1830.breaking.rst

+Mark the easy_install script and setuptools command as deprecated, and use `pip <https://pip.pypa.io/en/stable/>`_ when available to fetch/build wheels for missing ``setup_requires``/``tests_require`` requirements, with the following differences in behavior:
+ * support for ``python_requires``
+ * better support for wheels (proper handling of priority with respect to PEP 425 tags)
+ * PEP 517/518 support
+ * eggs are not supported
+ * no support for the ``allow_hosts`` easy_install option (``index_url``/``find_links`` are still honored)
+ * pip environment variables are honored (and take precedence over easy_install options)

changelog.d/1909.breaking.rst

+Mark the easy_install script and setuptools command as deprecated, and use `pip <https://pip.pypa.io/en/stable/>`_ when available to fetch/build wheels for missing ``setup_requires``/``tests_require`` requirements, with the following differences in behavior:
+ * support for ``python_requires``
+ * better support for wheels (proper handling of priority with respect to PEP 425 tags)
+ * PEP 517/518 support
+ * eggs are not supported
+ * no support for the ``allow_hosts`` easy_install option (``index_url``/``find_links`` are still honored)
+ * pip environment variables are honored (and take precedence over easy_install options)