connect: make daft spark an optional, opt-in feature.

[universalmind303]

Is your feature request related to a problem?

Most users don't have a need for daft connect, and it shouldn't be included as the default.

Describe the solution you'd like

normal installation without spark connect api.

pip install getdaft

# does not work
from daft.daft import connect_start

install optional spark connect

pip install getdaft[spark]

# works
from daft.daft import connect_start

Describe alternatives you've considered

No response

Additional Context

No response

Would you like to implement a fix?

No

[universalmind303]

will likely depend on #3497