Better IPFS as a library constructor

[aschmahmann]

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.

[MichaelMure]

Seems like a good idea to me. I've used IPFS as a library and the construction feels fairly brittle.