[meta] Remove support for IE11

Moving this down to major since it's not really time sensitive, we just need to finish off the child issues, some of which are 11.x only like dependency removals.

$ grep -ri IE11 --exclude-dir="node_modules" --exclude-dir="assets" core
core/themes/claro/js/tableselect.js:        // is preferable, but not supported by IE11.
core/themes/claro/js/tableselect.js:          // Determine add/remove with ternary since IE11 does not support the

Made an issue for this, 📌 Remove IE11 Support from Olivero Active