[Metadata] Fix several connection-related problems

1) Test on SQLite file should add metadata read:

With no password provided, Open() will NOT fail on a password-protected SQLite database, as you would expect! What fails is any subsequent data or metadata operation on that open file.

TODO: try to get number of tables, to check actual connection.

see this

2) Proper version/edition read for file-based databases, before opening db.

3) Inform when file not found, for file-based databases.

4) Access provider missing, for MDB/ACCDB.

5) Fix SQLite edition reading.

6) If connection failed, check right server name, server available, port open etc, and provide better error (generic) error message.

7) Reorganize DTypeInfos

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