mudskipper and shetland window fix (shiptest-ss13#3426)

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## About The Pull Request
Added windows to the mudskipper and shetland's engines as well for
consistency see shiptest-ss13#3434 for the Kilo fixes too.

Also seperated the Shetland's engine rooms so both buttons don't open
both sides.
Now the button in each engine room will open only it's respective side.

## Changelog

:cl:
fix: Added windows to the mudskipper and shetland's engines.
fix: Adjusted the blast doors which open on the Shetland's engines.
/:cl:

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_maps/shuttles/independent/independent_mudskipper.dmm

@@ -1096,6 +1096,9 @@
 	dir = 4;
 	id = "mudskipper_engine"
 	},
+/obj/structure/window/reinforced{
+	dir = 8
+	},
 /turf/open/floor/plating,
 /area/ship/engineering/engine)
 "zR" = (
@@ -1670,6 +1673,9 @@
 	dir = 4;
 	id = "mudskipper_engine"
 	},
+/obj/structure/window/reinforced{
+	dir = 8
+	},
 /turf/open/floor/plating,
 /area/ship/engineering/engine)
 "MK" = (

_maps/shuttles/independent/independent_shetland.dmm

@@ -1492,7 +1492,7 @@
 	},
 /obj/machinery/button/door{
 	dir = 1;
-	id = "amogusthrusters";
+	id = "shetportthrusters";
 	name = "Thruster Lockdown";
 	pixel_y = -21
 	},
@@ -2297,7 +2297,7 @@
 	pixel_y = 5
 	},
 /obj/machinery/button/door{
-	id = "amogusthrusters";
+	id = "shetstarboardengine";
 	name = "Thruster Lockdown";
 	pixel_y = 24
 	},
@@ -2748,11 +2748,14 @@
 	},
 /obj/machinery/door/poddoor{
 	dir = 4;
-	id = "amogusthrusters"
+	id = "shetstarboardengine"
 	},
 /obj/effect/turf_decal/industrial/warning{
 	dir = 4
 	},
+/obj/structure/window/reinforced{
+	dir = 8
+	},
 /turf/open/floor/plating,
 /area/ship/maintenance/starboard)
 "wU" = (
@@ -4423,11 +4426,14 @@
 	},
 /obj/machinery/door/poddoor{
 	dir = 4;
-	id = "amogusthrusters"
+	id = "shetportthrusters"
 	},
 /obj/effect/turf_decal/industrial/warning{
 	dir = 4
 	},
+/obj/structure/window/reinforced{
+	dir = 8
+	},
 /turf/open/floor/plating,
 /area/ship/maintenance/port)
 "Lx" = (
@@ -4989,11 +4995,14 @@
 	},
 /obj/machinery/door/poddoor{
 	dir = 4;
-	id = "amogusthrusters"
+	id = "shetportthrusters"
 	},
 /obj/effect/turf_decal/industrial/warning{
 	dir = 4
 	},
+/obj/structure/window/reinforced{
+	dir = 8
+	},
 /turf/open/floor/plating,
 /area/ship/maintenance/port)
 "PR" = (
@@ -5157,11 +5166,14 @@
 	},
 /obj/machinery/door/poddoor{
 	dir = 4;
-	id = "amogusthrusters"
+	id = "shetstarboardengine"
 	},
 /obj/effect/turf_decal/industrial/warning{
 	dir = 4
 	},
+/obj/structure/window/reinforced{
+	dir = 8
+	},
 /turf/open/floor/plating,
 /area/ship/maintenance/starboard)
 "Ri" = (