feature/exclude-expired-entries--option

[Drealise]

Cfr. the discussion at https://forum.kee.pm/t/kee-plugin-shows-expired-entries/3861, some users would find it useful to have an option to hide expired entries from the list of matching results presented by the Kee browser add-on.
For this, the following PR has been created: #346

PS. In order for the add-on to be able to filter out expired entries, the expiration-related metadata ("expires", "expiryTime") must be exposed by the KeePassRPC plugin.
For this, the following PR has been created: kee-org/keepassrpc#156

• corresponding issue: feature/expose-expiration-data keepassrpc#157