add timeout support for function invocations

[valt-x]

Add timeout option to Supabase.Functions.invoke/3
Support for custom timeout values (defaults to 15 seconds)

still its looks hard cuz js has native choices ,even super heros has some drawbacks
Resolves #4

[zoedsoupe]

thanks for the contribution!

[zoedsoupe]

did you validate that only the receive_timeout is sufficient? as we're always using Fetcher.stream, then probably yes, but it would be nice to ensure that also request_timeout isn't necessary since when not passing on_response callback

as far as i know receive_timeout is only for streaming and the internal message passing timeout from Finch

[valt-x]

Thanks for your response

Yeah receive timeout is not needed for now just added for future uses like passing messages between rpc and functions or inter messages and importantly chain requests

If you don't need , tell me I will remove it

[zoedsoupe]

ok, makes sense, but that is sufficient for implementing timeout? maybe we can add the request_timeout option too with the same value? wdyt?

[valt-x]

Good catch! Looking at Finch docs:

 * receive_timeout: per-chunk timeout (15s default)
 * request_timeout: overall response timeout (infinity default, HTTP/1 only)

Since we want comprehensive timeout support, I should add both. The current
implementation only handles chunk timeouts but not overall request timeouts.
I'll update to include both options with the same timeout value.