Remove enc_write_state

Remove enc_write_state

This field was used to track whether a cipher ctx was valid for writing
or not, and also whether we should write out plaintext alerts. With the new
record layer design we no longer need to track whether a cipher ctx is valid
since the whole record layer will be aborted if it is not. Also we have a
different mechanism for tracking whether we should write out plaintext
alerts. Therefore this field is removed from the SSL object.

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19343)