Stores a group session as a base64 string. Encrypts the session using the
supplied key. Returns the length of the session on success.
Returns olm_error() on failure. If the pickle output buffer
is smaller than olm_pickle_inbound_group_session_length() then
olm_inbound_group_session_last_error() will be "OUTPUT_BUFFER_TOO_SMALL"
Stores a group session as a base64 string. Encrypts the session using the supplied key. Returns the length of the session on success.
Returns olm_error() on failure. If the pickle output buffer is smaller than olm_pickle_inbound_group_session_length() then olm_inbound_group_session_last_error() will be "OUTPUT_BUFFER_TOO_SMALL"