formatting: bulk remove trailing whitespaces

Do not touch vendorized files (e.g. libraries that were imported from external
projects).

No functional changes.

Command:
    find . -name '*.<EXTENSION>' -type f -print0 | xargs -0 sed -i 's/[[:space:]]*$//'

src/node/db/Pad.js

@@ -460,7 +460,7 @@ Pad.prototype.remove = async function remove() {
   // none of the operations except getting the group depended on callbacks
   // so the database operations here are just started and then left to
   // run to completion
- 
+
   // is it a group pad? -> delete the entry of this pad in the group
   if (padID.indexOf("$") >= 0) {