Integrated circuits for modular computers (#80530)

## About The Pull Request
This PR integrates circuits for modular computers and a good bits of
their programs.
The peculiarity here is that modular computers have no fixed amount of
unremovable components (except the base one with just a couple ports for
now), instead, they're added and removed along with programs. With a few
exceptions (such as the messenger and signaler), for these program
circuits to work, their associated program has to be either open or in
the background.

For a reason or another, not all programs have a circuit associated to
them, still, however the programs with a circuit are still a handful.
They are:
- Nanotrasen Pay System
- Notepad
- SiliConnect
- WireCarp
- MODsuit Control
- Spectre Meter
- Direct Messenger*
- LifeConnect
- Custodial Locator
- Fission360
- Camera
- Status Display
- SignalCommander

*By the by, sending messages has a cooldown, so it shouldn't be as
spammy. If it turns out to not be enough, I can make it so messages from
circuit will be ignored by other messenger circuits.

The PR is no longer WIP.

## Why It's Good For The Game
I believe modular computers could make for some interesting setups with
circuits, since they're fairly flexible and stocked with features unlike
many other appliances, therefore also a speck more abusable, though
limits, cooldowns, logging and sanitization have been implemented to
keep it in check.

## Changelog

🆑
add: Modular Computers now support integrated circuits. What can be done
with them depends on the programs installed and whether they're running
(open or background).
add: Modular Consoles (the machinery) now have a small backup cell they
draw power from if the power goes out.
/🆑

code/modules/modular_computers/file_system/programs/notepad.dm

@@ -8,6 +8,7 @@
 	tgui_id = "NtosNotepad"
 	program_icon = "book"
 	can_run_on_flags = PROGRAM_ALL
+	circuit_comp_type = /obj/item/circuit_component/mod_program/notepad
 
 	var/written_note = "Congratulations on your station upgrading to the new NtOS and Thinktronic based collaboration effort, \
 		bringing you the best in electronics and software since 2467!\n\
@@ -19,7 +20,8 @@
 		Quarter - Either sides of Aft\n\
 		Bow - Either sides of Fore"
 
-/datum/computer_file/program/notepad/ui_act(action, list/params, datum/tgui/ui)
+/datum/computer_file/program/notepad/ui_act(action, list/params, datum/tgui/ui, datum/tgui/ui, datum/ui_state/state)
+	. = ..()
 	switch(action)
 		if("UpdateNote")
 			written_note = params["newnote"]
@@ -31,3 +33,34 @@
 	data["note"] = written_note
 
 	return data
+
+/obj/item/circuit_component/mod_program/notepad
+	associated_program = /datum/computer_file/program/notepad
+	///When the input is received, the written note will be set to its value.
+	var/datum/port/input/set_text
+	///The written note output, sent everytime notes are updated.
+	var/datum/port/output/updated_text
+
+/obj/item/circuit_component/mod_program/notepad/populate_ports()
+	. = ..()
+	set_text = add_input_port("Set Notes", PORT_TYPE_STRING)
+	updated_text = add_output_port("Updated Notes", PORT_TYPE_STRING)
+
+/obj/item/circuit_component/mod_program/notepad/register_shell(atom/movable/shell)
+	. = ..()
+	RegisterSignal(associated_program, COMSIG_UI_ACT, PROC_REF(on_note_updated))
+
+/obj/item/circuit_component/mod_program/notepad/unregister_shell()
+	UnregisterSignal(associated_program, COMSIG_UI_ACT)
+	return ..()
+
+/obj/item/circuit_component/mod_program/notepad/proc/on_note_updated(datum/source, mob/user, action, list/params)
+	SIGNAL_HANDLER
+	if(action == "UpdateNote")
+		updated_text.set_output(params["newnote"])
+
+/obj/item/circuit_component/mod_program/notepad/input_received(datum/port/port)
+	var/datum/computer_file/program/notepad/pad = associated_program
+	pad.written_note = set_text.value
+	SStgui.update_uis(pad.computer)
+	updated_text.set_output(pad.written_note)