Give the full server struct to the FDW when instanciating it

[remilapeyre]

The complete SQL command to create a foreign data wrapper is

CREATE SERVER [ IF NOT EXISTS ] server_name [ TYPE 'server_type' ] [ VERSION 'server_version' ]
    FOREIGN DATA WRAPPER fdw_name
    [ OPTIONS ( option 'value' [, ... ] ) ]

At this time only the options are given to the Foreign Data Wrapper implementation. This patch changes the signature of ForeignDataWrapper::new() to give it the full structure that matches PostgreSQL ForeignServer to expose the server_name, server_type and server_version attributes.

[burmecia]

Great work, thanks for the PR!