Adds a preference to adjust emissive bloom size (#94722)

## About The Pull Request

Adds a slider to the gameplay tab which allows users to control the size
of the emissive bloom.

## Why It's Good For The Game

This is mostly visual and doesn't have a noticeable performance impact,
but some people might find it distracting or might want a stronger bloom
for prettier lights.

## Changelog
🆑
qol: Added a preference to adjust emissive bloom size
/🆑

code/modules/client/preferences/emissive_bloom.dm

@@ -0,0 +1,28 @@
+/// Size of the bloom filter applied to the emissive plane, mostly as a visual preference
+/datum/preference/numeric/emissive_bloom
+	category = PREFERENCE_CATEGORY_GAME_PREFERENCES
+	savefile_key = "emissive_bloom"
+	savefile_identifier = PREFERENCE_PLAYER
+
+	minimum = 0
+	maximum = MAXIMUM_EMISSIVE_BLOOM_SIZE
+
+/datum/preference/numeric/emissive_bloom/create_default_value()
+	return DEFAULT_EMISSIVE_BLOOM_SIZE
+
+/datum/preference/numeric/emissive_bloom/apply_to_client(client/client, value)
+	// Update the plane master filter
+	var/datum/hud/my_hud = client.mob?.hud_used
+	if(!my_hud)
+		return
+
+	for(var/atom/movable/screen/plane_master/bloom as anything in my_hud.get_true_plane_masters(RENDER_PLANE_EMISSIVE_BLOOM))
+		if (!bloom.get_filter("emissive_bloom"))
+			if (value)
+				bloom.add_filter("emissive_bloom", 2, bloom_filter(threshold = COLOR_BLACK, size = value, offset = ceil(value / 2)))
+			continue
+
+		if (value)
+			bloom.modify_filter("emissive_bloom", list("size" = value, "offset" = ceil(value / 2)))
+		else
+			bloom.remove_filter("emissive_bloom")