Extract reading of input i/o to input

And add the ability of other modules to listen to either
the final result (a `Key`) or tap into the input as it is read

src/musicplayer.gleam

@@ -1,8 +1,22 @@
-import gleam/erlang/process
+import gleam/erlang/process.{type Name}
+
+import input/input.{type Listener}
+import input/key.{type Key}
 import mpv/mpv
 
 pub fn main() -> Nil {
   let exit = process.new_subject()
-  let assert Ok(_) = mpv.new(exit)
+
+  // `inject_input` is created by name to allow the `input` process that
+  // owns `read_input` to be able to register and receive from it,
+  //  while the any other processes can use the name reference to
+  // inject input
+  let inject_input_name: Name(Key) = process.new_name("inject_input")
+
+  let assert Ok(mpv_listener) = mpv.new(exit)
+
+  let listeners: List(Listener) = [mpv_listener]
+
+  input.new(listeners, inject_input_name)
   process.receive_forever(exit)
 }