Moves revolution code of out of flash code, fixes April Fool conversion forcesay never working in any cirumstances (#74411)

## About The Pull Request

- Signallizes head revolutionary flash conversion code, moving it out of
core flash code.
- Removes "tacticool" flashing from head revs, but they can still
convert from any direction
 
- Fixes April Fools "You son of a bitch! I'm in" force say never
working.
   - Revs are muted on conversion so they couldn't talk.
       - Fixed by only muting revs on non-holidays
   - Cultists are unconscious on conversion so they couldn't talk
       - Fixed by only unconscious-ing cultists on non-holidays
- Brainwash victims are more often than not unconscious / asleep so they
couldn't talk
       - Just left this one. 

- Reduced the chance of them occurring and limits it to April Fools only
- A 1% chance of the force says ocurring means they will happen pretty
much once a week, given multiple rev / cult rounds happen every week and
on average like, 20 people are converted. A little absurd, it's good
that it never worked?

## Why It's Good For The Game

Antag code in core item code is bad

It's funny this meme has existed for like 2, 3 years now? No one's
tested it, it's never worked

## Changelog

🆑 Melbert
refactor: Removes Rev code from core flash code
fix: Getting converted on April Fools now triggers the meme force say as
always intended
del: The meme force say can no longer trigger on any day (it didn't work
before anyways)
/🆑

code/modules/unit_tests/_unit_tests.dm

@@ -181,6 +181,7 @@
 #include "reagent_recipe_collisions.dm"
 #include "reagent_transfer.dm"
 #include "resist.dm"
+#include "rev_conversion.dm"
 #include "say.dm"
 #include "screenshot_antag_icons.dm"
 #include "screenshot_basic.dm"

code/modules/unit_tests/rev_conversion.dm

@@ -0,0 +1,22 @@
+/// Tests that headrevs can convert people by clicking on them with flashes
+/datum/unit_test/revolution_conversion
+
+/datum/unit_test/revolution_conversion/Run()
+	var/mob/living/carbon/human/leader = allocate(/mob/living/carbon/human/consistent, run_loc_floor_bottom_left)
+	var/mob/living/carbon/human/peasant = allocate(/mob/living/carbon/human/consistent, run_loc_floor_bottom_left)
+
+	leader.mind_initialize()
+	leader.mock_client = new()
+	peasant.mind_initialize()
+	peasant.mock_client = new()
+
+	var/datum/antagonist/rev/head/lead_datum = leader.mind.add_antag_datum(/datum/antagonist/rev/head)
+	var/datum/team/revolution/revolution = lead_datum.get_team()
+
+	var/obj/item/assembly/flash/handheld/converter = allocate(/obj/item/assembly/flash/handheld)
+	leader.put_in_active_hand(converter, forced = TRUE)
+	leader.ClickOn(peasant)
+
+	TEST_ASSERT(peasant.IsParalyzed(), "Peasant was not paralyzed after being flashed by the leader") // Flash paralyze
+	TEST_ASSERT(peasant.IsStun(), "Peasant was not stunned after being converted by the leader") // Conversion stun
+	TEST_ASSERT_EQUAL(length(revolution.members), 2, "Expected revolution to have 2 members after the leader flashes the peasant.")