Before this commit, when user follows odoobot chat onboarding and
sends a canned response at the canned response step, odoobot did
not validate the message with the canned response.
This is caused by RPC `message_post` that filters out values that
are not message fields, such as `canned_response_ids`.
This commit fixes the issue by adding a non-stored field
`canned_response_ids` to `mail.message`. This requires the reverse
relation too, `message_ids` in `mail.shortcodes` (= the model for
canned responses).
Task-Id 2058455
closesodoo/odoo#36411
Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>