add test data

__tests__/files/mixed/01-gmail-to-outlook/r_htmlContent.html

...sts__/files/mixed/01-gmail-to-outlook/r_plainContent.data

__tests__/files/mixed/01-gmail-to-outlook/s_htmlContent.html

...sts__/files/mixed/01-gmail-to-outlook/s_plainContent.data

__tests__/files/mixed/02-macos-to-gmail/r_htmlContent.html

__tests__/files/mixed/02-macos-to-gmail/r_plainContent.data

__tests__/files/mixed/02-macos-to-gmail/s_htmlContent.html

__tests__/files/mixed/02-macos-to-gmail/s_plainContent.data

__tests__/files/mixed/03-gmail-to-outlook/r_htmlContent.html

...sts__/files/mixed/03-gmail-to-outlook/r_plainContent.data

__tests__/files/mixed/03-gmail-to-outlook/s_htmlContent.html

...sts__/files/mixed/03-gmail-to-outlook/s_plainContent.data

__tests__/files/mixed/04-macos-to-gmail/r_htmlContent.html

__tests__/files/mixed/04-macos-to-gmail/r_plainContent.data

__tests__/files/mixed/04-macos-to-gmail/s_htmlContent.html

__tests__/files/mixed/04-macos-to-gmail/s_plainContent.data

__tests__/files/mixed/05-gmail-to-outlook/r_htmlContent.html

...sts__/files/mixed/05-gmail-to-outlook/r_plainContent.data

__tests__/files/mixed/05-gmail-to-outlook/s_htmlContent.html

...sts__/files/mixed/05-gmail-to-outlook/s_plainContent.data