Impacted versions: 8-11

## Current behavior:

If during an XMLRPC call you try to get anything from `http.request`, you'd get a `RuntimeError` such as this one:

```
Traceback (most recent call last):
  File "/opt/odoo/custom/src/odoo/odoo/service/wsgi_server.py", line 56, in xmlrpc_return
    result = odoo.http.dispatch_rpc(service, method, params)
  File "/opt/odoo/custom/src/odoo/odoo/http.py", line 118, in dispatch_rpc
    result = dispatch(method, params)
  File "/opt/odoo/custom/src/odoo/odoo/service/common.py", line 57, in dispatch
    return g[exp_method_name](*params)
  [...]
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/local.py", line 343, in __getattr__
    return getattr(self._get_current_object(), name)
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/local.py", line 302, in _get_current_object
    return self.__local()
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/local.py", line 135, in _lookup
    raise RuntimeError(\'object unbound\')
RuntimeError: object unbound
```

This renders imposible in practice to fix issues such as https://github.com/OCA/server-tools/issues/1125 or to implement https://github.com/odoo/odoo/pull/22212#issuecomment-380425764.

## Expected behavior:

XML-RPC calls should have request, since after all they belong to one. Otherwise, at least there should be an alternate way to access the request parameters.

Fix for v12: https://github.com/odoo/odoo/pull/24187

@Tecnativa
odoo/http.py
context = dict(self.context)
        self.session._fix_lang(context)
        self.context = context
        return context["lang"]
    @lazy_property
    def session(self):
        """ :class:`OpenERPSession` holding the HTTP session data for the
        current http session
        """
        return self.httprequest.session
    def __enter__(self):
        _request_stack.push(self)
        return self
    def __exit__(self, exc_type, exc_value, traceback):
        _request_stack.pop()
        if self._cr:
            if exc_type is None and not self._failed:
                self._cr.commit()
                if self.registry:
                    self.registry.signal_changes()
            elif self.registry:
                self.registry.reset_changes()
            self._cr.close()
        
        self.disable_db = True
        self.uid = None
    def set_handler(self, endpoint, arguments, auth):