Adds fire/air alarms (#5018)

Co-authored-by: Vera Aguilera Puerto <6766154+Zumorica@users.noreply.github.com>
Co-authored-by: E F R <602406+Efruit@users.noreply.github.com>
Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>
Co-authored-by: metalgearsloth <comedian_vs_clown@hotmail.com>

Content.Server/Atmos/Monitor/Components/AtmosAlarmableComponent.cs

@@ -0,0 +1,48 @@
+using System.Collections.Generic;
+using Content.Server.Power.Components;
+using Content.Shared.Atmos.Monitor;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Serialization.Manager.Attributes;
+using Robust.Shared.ViewVariables;
+
+namespace Content.Server.Atmos.Monitor.Components
+{
+    // AtmosAlarmables are entities that can be alarmed
+    // by a linked AtmosMonitor (alarmer?) if a threshold
+    // is passed in some way. The intended use is to
+    // do something in case something dangerous happens,
+    // e.g., activate firelocks in case a temperature
+    // threshold is reached
+    //
+    // It goes:
+    //
+    // AtmosMonitor -> AtmosDeviceUpdateEvent
+    // -> Threshold calculation
+    // -> AtmosMonitorAlarmEvent
+    // -> Everything linked to that monitor (targetted)
+
+    /// <summary>
+    ///     A component to add to device network devices if you want them to be alarmed
+    ///     by an atmospheric monitor.
+    /// </summary>
+    [RegisterComponent]
+    public class AtmosAlarmableComponent : Component
+    {
+        public override string Name => "AtmosAlarmable";
+
+        [ViewVariables]
+        public List<EntityUid> LinkedMonitors { get; set; } = new();
+
+        [ViewVariables] public AtmosMonitorAlarmType LastAlarmState = AtmosMonitorAlarmType.Normal;
+        [ViewVariables] public AtmosMonitorAlarmType HighestNetworkState = AtmosMonitorAlarmType.Normal;
+        [ViewVariables] public bool IgnoreAlarms { get; set; } = false;
+
+        /// <summary>
+        ///     List of prototypes that this alarmable can be
+        ///     alarmed by - must be a prototype with AtmosMonitor
+        ///     attached to it
+        /// </summary>
+        [DataField("alarmedBy")]
+        public List<string> AlarmedByPrototypes { get; } = new();
+    }
+}