This change switches the Meta/import-wpt-test.py script to using the
standard html.parser module rather than BeautifulSoup.
Otherwise, without this change, when a contributor first tries to run
the script, if they don’t have BeautifulSoup installed, it will fail.
Note that this patch also includes an unrelated small change that
switches to using os.path.normpath — rather than Path.absolute() — to
“normalize” the destination names of the downloaded test files.
(cherry picked from commit 286511c4cf9dcd985882c9bbb2de42b01e7494a9)
