[IMP] website_mail: simplify helpers for external post

After removing the `sha_in` params a while ago, we get rid of
the deprecated `token_field` option.

- Make `token_field` a model attribute, so that each model can easily
  define the token field that should be used, and it does not need
  to be passed around all the time anymore.

- Rename `_special_access_object()` to `_has_token_access()`, much more
  readable since it returns a bool

- Do not forward the `attachment_ids` keyword arg to message_post,
  as it sometimes contains unrelated IDs (the helper is not meant
  to post attachments anyway)

- Update callers accordingly

0 files changed, 0 insertions, 0 deletions