Use solid/filled Font Awesome icons for consistency.

Some of the "open" icons are not in the free FA tier, so rather than mix
the two we should use solid icons everywhere.

static/icons/edit.svg

@@ -1 +1 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16"><path d="M15 16H1c-.552 0-1-.447-1-1V1c0-.552.448-1 1-1h10v2H2v12h12V5h2v10c0 .553-.447 1-1 1zM5 12c-.256 0-.512-.098-.707-.293-.391-.391-.391-1.023 0-1.414l10-10c.391-.391 1.023-.391 1.414 0s.391 1.023 0 1.414l-10 10C5.512 11.902 5.256 12 5 12z"/></svg>
+<svg aria-hidden="true" focusable="false" data-prefix="fas" data-icon="edit" class="svg-inline--fa fa-edit fa-w-18" role="img" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 576 512"><path fill="currentColor" d="M402.6 83.2l90.2 90.2c3.8 3.8 3.8 10 0 13.8L274.4 405.6l-92.8 10.3c-12.4 1.4-22.9-9.1-21.5-21.5l10.3-92.8L388.8 83.2c3.8-3.8 10-3.8 13.8 0zm162-22.9l-48.8-48.8c-15.2-15.2-39.9-15.2-55.2 0l-35.4 35.4c-3.8 3.8-3.8 10 0 13.8l90.2 90.2c3.8 3.8 10 3.8 13.8 0l35.4-35.4c15.2-15.3 15.2-40 0-55.2zM384 346.2V448H64V128h229.8c3.2 0 6.2-1.3 8.5-3.5l40-40c7.6-7.6 2.2-20.5-8.5-20.5H48C21.5 64 0 85.5 0 112v352c0 26.5 21.5 48 48 48h352c26.5 0 48-21.5 48-48V306.2c0-10.7-12.9-16-20.5-8.5l-40 40c-2.2 2.3-3.5 5.3-3.5 8.5z"></path></svg>