Beyond just an extraction, this is also a simplification. It removes two
variables: `org-roam-date-filename-format` and
`org-roam-date-title-format`, in favour of directly specifying them in
the `org-roam-dailies-capture-templates`.
`org-roam--file-for-time` is also vastly simplified to use org-capture's
default time expansion utilities, by setting the capture template's
`:default-time` appropriately.
