Add Logging

[samansmink]

With DuckDB's new logging infra, we can hook up the delta logging to the DuckDB logger to allow us to expose the kernel logging in a clean way to DuckDB users.

To enable:

set enable_logging=true;
set delta_kernel_logging=true;
set logging_level='DEBUG'

FROM delta_scan('...');

FROM duckdb_logs;

will now show entries such as:

2025-01-13 12:30:22.033	delta.Kernel	DEBUG	[delta_kernel_ffi] ffi/src/lib.rs@363 : dropping engine interface 	DATABASE	NULL	NULL	NULL
2025-01-13 12:30:22.033	delta.Kernel	DEBUG	[delta_kernel_ffi] ffi/src/lib.rs@594 : engine released snapshot 	DATABASE	NULL	NULL	NULL

Note that the 'delta_kernel_logging' setting was added to explicitly enable kernel log forwarding, because enabling them by default might be potentially expensive even if DuckDB logging is enabled. Also note that disabling kernel logging forwarding is not possible because the ffi has no way of unregistering the callback.