Fix #5730: document older DuckDB versions internally, and state which DuckDB version a specific file came from

[Mytherin]

This PR adapts the error message thrown when opening an older version of DuckDB by notifying the user which DuckDB version was used to create a specific file, e.g.:

$ duckdb test/storage/bc/db_04.db
Error: unable to open database "test/storage/bc/db_04.db": IO Error: Trying to read a database file with version number 33, but we can only read version 40.
The database file was created with DuckDB version v0.3.3, v0.3.4 or v0.4.0.

The storage of DuckDB is not yet stable; newer versions of DuckDB cannot read old database files and vice versa.
The storage will be stabilized when version 1.0 releases.

For now, we recommend that you load the database file in a supported version of DuckDB, and use the EXPORT DATABASE command followed by IMPORT DATABASE on the current version of DuckDB.

See the storage page for more information: https://duckdb.org/internals/storage

We also link to the new storage info page which documents the storage version further.