Sync with soap-client repository, version 3.1.1

Sync with soap-client repository, version 3.1.1

* lisp/net/soap-client.el (soap-encode-xs-complex-type): Fix error
message.
(soap-find-port): Delete trailing whitespace.
(soap-find-operation): Fix documentation and rename parameter.
(soap-find-port): Likewise.
(soap-operation-arity): Likewise.

* lisp/net/soap-client.el: Update copyright years.
(soap-warning): Fix docstring quoting.
(soap-decode-date-time): Likewise.
(soap-validate-xs-simple-type): Remove tabs for indentation.
* lisp/net/soap-inspect.el: Update copyright years.

* lisp/net/soap-client.el (soap-encode-xs-basic-type): Do not
assume xsd:base64Binary values are UTF-8 strings.
(soap-decode-xs-basic-type): Likewise.
(soap-invoke): Document xsd:base64Binary handling.

* lisp/net/soap-client.el (soap-find-port, soap-find-operation)
(soap-operation-arity): new defuns
(soap-invoke-internal): use soap-find-port, soap-find-operation.

Co-authored-by: Alex Harsanyi  <AlexHarsanyi@gmail.com>