Fixes many WPCS errors and warnings
Also:
* Partly removes excessive php opening/closing tags.
* Uses printf for better readability in loop-templates/content-none.php.
* Adds understrap_kses_title() to escape post titles.
* Adds understrap_escape_the_archive_description() to escape the archive description.
* Fixes missing '__' after esc_html in author.php.
* Updates the phpcs.xml to reflect all the changes.
* Updates composer dependencies and scripts.
IanDelMar
Gary Kealy
Stefan Grassberger
Alex Wright
Rami Yushuvaev
Stef Kariotidis
koenemann