IPC protocol should be buffer based, not JSON based

[joaomoreno]

• Make IPC Buffer based, instead of any based
• Provide better buffer serialization for buffer data arguments

[joaomoreno]

Pushed the first step. This allows us full control at the protocol layer as to how to serialize/deserialize things; namely, if that thing is a buffer, everything's easier.

One issue emerged. Because the abstraction is one layer below, we possibly lost performance on two areas:

• IPC over child processes using fork (ipc.cp.ts)
• IPC over Electron

Both these implementations do not support Buffers currently. Here's my proposal for each:

• Remove protocol work from ipc.cp.ts and make it dependent on ipc.net.ts, since that implementation works using named pipes and sockets. This will let us be independent from node's fork and serialization, which is a good thing anyway.
• Wait for Electron 3 which brings Buffer support over IPC: Fix support for typed arrays in remote/rpc-server electron/electron#13055. This is fine since we send very small and few messages over Electron IPC. Another alternative here is to also ditch Electron IPC and just use ipc.net.ts as well.

[joaomoreno]

Second step pushed. Buffers can now be used in the following places:

• Promise request arg
• Promise resolution result
• Event request arg
• Event data