Better IPFS as a library constructor

We can currently get an IpfsNode by calling

https://github.com/ipfs/go-ipfs/blob/2ae5c52f4f0f074864ea252e90e72e8d5999caba/core/builder.go#L27

Unfortunately the `BuildCfg` is covers just a fraction of the sorts of options a custom IpfsNode my want to utilize. I think it would be very useful to have some constructor that looks something like:

`NewNode(ctx context.Context, option... IpfsNodeOption) (*IpfsNode, error)` and we can start to slowly expand the number of IpfsNode options. This also allows us to more easily deal with subcomponent options (e.g. passing options like `WithExchange(BitswapExchange(bitswapOptions...))`).

This could allow us to hide away the internals of the fx dependency injection while still utilizing it internally.