Update uses of if-let and when-let

Update uses of if-let and when-let

* lisp/dom.el (dom-previous-sibling):
* lisp/emacs-lisp/package.el (package--with-work-buffer):
(package--sort-deps-in-alist, package--sort-by-dependence):
(package-install-from-archive, package-install):
(package-menu-execute, package-menu--populate-new-package-list):
* lisp/filenotify.el (file-notify--rm-descriptor):
(file-notify--event-watched-file, file-notify--event-file-name):
(file-notify--event-file1-name, file-notify-rm-watch):
(file-notify-valid-p):
* lisp/gnus/message.el (message-toggle-image-thumbnails):
* lisp/gnus/nnimap.el (nnimap-request-move-article):
* lisp/ibuf-ext.el (ibuffer-repair-saved-filters):
* lisp/mpc.el (mpc-format):
* lisp/net/eww.el (eww-tag-meta, eww-process-text-input):
(eww-save-history):
* lisp/net/shr.el (shr-tag-base, shr-tag-object, shr-make-table-1):
* lisp/progmodes/prog-mode.el (prettify-symbols--post-command-hook):
* lisp/svg.el (svg-remove):
* lisp/textmodes/css-mode.el (css--named-color):
(css--colon-inside-funcall):
* lisp/textmodes/sgml-mode.el (html-current-buffer-classes):
(html-current-buffer-ids): Use if-let* and when-let* instead.