[FEAT] Add daft.context.set_config function for setting configurations globally

[jaychia]

1. Adds a daft.context.set_config(**kwargs) method for users to set configuration parameters in Daft
2. Adds a new common/daft-config crate to house the DaftConfig struct
3. Thread PyDaftConfig {config: Arc<DaftConfig>} through the pyo3 layer for any functions that require access to configuration values: use daft.context.get_context().daft_config to retrieve the current PyDaftConfig from Python

.set_config() in action:

NOTE: Because we leverage our current daft.context Python global singleton machinery, note that the configs are probably not being propagated correctly in a multiprocessing/Ray worker environment to separate Python processes.

For this to work, we will need to correctly initialize any Ray workers with the current DaftContext, or abandon the DaftContext machinery for something more suitable.

[samster25]

LGTM