* started building out providers chapter for the book, updated the intro for the chapter as well as the Http section. Added advanced usage section.
* Updated WS and Ipc chapter, working on usage, furthering descriptions
* updated ipc section, added code snippets
* updating the ws section, adding code snippet for example using the subscribe_pending_tx method
* Updated the provider section to include info on the ens and _node_client fields, udpated the advanced usage section to include CallBuilder and raw_call.
* added examples to ipc and ws chapters, cleared todos
* added note about windows ipc named pipes
* added spaces to comments
* fixed comment, removed all usage of unwrap()
* updated Http provider to initialize without ::<Http::
* updated the Ipc provider to initialize without setting the polling interval
* Update book/providers/providers.md
Co-authored-by: Georgios Konstantopoulos <me@gakonst.com>