[repoapi] add a connect function This function takes a repo and authentication information to open a new Session and return a ClientConnection associated to it.

[client-connection] add an auto-close property for ClientConnection The next commit introduce a connect function that open a new Session and return an associated ClientConnection. The Session should not be used by anything else than the created ClientConnection, so we want to close it at the same time than the ClientConnection. The implementation in this changeset is simplistic. We probably want to move this notion in the session itself. This be improved once we have server side Connection

[cwuser] make CWUser callable, returning self for dbapi compatibility In the dbapi, Connection and Session have a ``user`` method to generated a user for a request In the repo api, Connection and Session have a user attribute inherited from SessionRequestBase prototype. This ugly hack allows to not break user of the user method. To ease transition from dbapi to repoapi we need the ClientConnection to be as compatible as possible with the dbapi. Adding this method goes in this direction. It'll get deprecated in the deprecation wave that will conclude the repoapi refactoring. related to #2503918

[client-connect] drop rqlst on rset returned client side The DBAPI used to drop the RQL syntax tree on rset to save bandwidth. We could stop doing it for In-memory client connection. However keeping the syntax tree leads to multiple tests failures. So we keep dropping it as the DBAPI always did. related to #2503918

[client-connection] add a repo property for dbapi compatibility To ease transition from dbapi to repoapi we need the ClientConnection to be as compatible as possible with the dbapi. Adding this method goes in this direction. It'll get deprecated in the deprecation wave that will conclude the repoapi refactoring. related to #2503918

[client-connection] add a connection property for dbapi compatibility To ease transition from dbapi to repoapi we need the ClientConnection to be as compatible as possible with the dbapi. Adding this method goes in this direction. It'll get deprecated in the deprecation wave that will conclude the repoapi refactoring. related to #2503918

[client-connection] add a sessionid property for dbapi compatibility To ease transition from dbapi to repoapi we need the ClientConnection to be as compatible as possible with the dbapi. Adding this method goes in this direction. It'll get deprecated in the deprecation wave that will conclude the repoapi refactoring. related to #2503918

[client-connection] add a cursor() method for dbapi compatibility To ease transition from dbapi to repoapi we need the ClientConnection to be as compatible as possible with the dbapi. Adding this method goes in this direction. It'll get deprecated in the deprecation wave that will conclude the repoapi refactoring. related to #2503918

[client-connection] add a request() method for dbapi compatibility To ease transition from dbapi to repoapi we need the ClientConnection to be as compatible as possible with the dbapi. Adding this method goes in this direction. It'll get deprecated in the deprecation wave that will conclude the repoapi refactoring. related to #2503918

[repoapi] introduce a basic ClientConnection class This is the new official way to access the repo from client side. It still access Session object directly as the server side connection is not up yet (and it's not up because it would have no user). Multiple follow up commit will install compatibility with the DBAPI. This will ease the migration from dbapi to repoapi. ClientConnection has no user yet but later commit will use it in the whole Web stack. related to #2503918