Provide a callback for running code on a supervisor after it starts, before it starts its children

[ToddG]

WHAT
Expose the init callback to Gleam.

WHY
As I understand the conversation, the Erlang/OTP GenServer Init Callback is where one might call proc_lib::set_label. However, the init callback is not exposed in Gleam.

USE CASE
I'd like to have labeled processes in the erlang observer to assist program debugging & documentation.

DISCUSSION
https://discordapp.com/channels/768594524158427167/1397286856290340894/1418250965554958337

RELATED
gleam-lang/erlang#88

[lpil]

Good idea, there's lots of times one would want to be able to do this.