Adds enough playtime requirements for jobs, we can turn off "days since reg" system

New job playtime requirements:
- Engineer: 5h
- Atmos tech: 5h
- MD: 3h
- Med Chemist: 5h
- Genetics: 3h
- Viro: 5h
- Paramedic: 3h
- Scientist: 5h
- Robotocist: 3h

With these requirements in place, we can turn off the
"USE_AGE_RESTRICTION_FOR_JOBS" system, and simply use playtime to gate
access to jobs instead.

code/game/jobs/job/engineering.dm

@@ -57,6 +57,8 @@
 	minimal_access = list(access_eva, access_engine, access_engine_equip, access_tech_storage, access_maint_tunnels, access_external_airlocks, access_construction, access_mineral_storeroom)
 	alt_titles = list("Maintenance Technician","Engine Technician","Electrician")
 	minimal_player_age = 7
+	exp_requirements = 300
+	exp_type = EXP_TYPE_CREW
 	outfit = /datum/outfit/job/engineer
 
 /datum/outfit/job/engineer
@@ -92,6 +94,8 @@
 	minimal_access = list(access_eva, access_atmospherics, access_maint_tunnels, access_external_airlocks, access_emergency_storage, access_construction, access_mineral_storeroom)
 	alt_titles = list("Atmospheric Technician")
 	minimal_player_age = 7
+	exp_requirements = 300
+	exp_type = EXP_TYPE_CREW
 	outfit = /datum/outfit/job/atmos
 
 /datum/outfit/job/atmos

code/game/jobs/job/medical.dm

@@ -52,6 +52,8 @@
 	minimal_access = list(access_medical, access_morgue, access_surgery, access_maint_tunnels)
 	alt_titles = list("Surgeon","Nurse","Coroner")
 	minimal_player_age = 3
+	exp_requirements = 180
+	exp_type = EXP_TYPE_CREW
 	outfit = /datum/outfit/job/doctor
 
 /datum/outfit/job/doctor
@@ -115,6 +117,8 @@
 	minimal_access = list(access_medical, access_chemistry, access_maint_tunnels, access_mineral_storeroom)
 	alt_titles = list("Pharmacist","Pharmacologist")
 	minimal_player_age = 7
+	exp_requirements = 300
+	exp_type = EXP_TYPE_CREW
 	outfit = /datum/outfit/job/chemist
 
 /datum/outfit/job/chemist
@@ -145,6 +149,8 @@
 	access = list(access_medical, access_morgue, access_surgery, access_chemistry, access_virology, access_genetics, access_research, access_mineral_storeroom)
 	minimal_access = list(access_medical, access_morgue, access_genetics, access_research, access_maint_tunnels)
 	minimal_player_age = 3
+	exp_requirements = 180
+	exp_type = EXP_TYPE_CREW
 	outfit = /datum/outfit/job/geneticist
 
 /datum/outfit/job/geneticist
@@ -177,6 +183,8 @@
 	minimal_access = list(access_medical, access_virology, access_maint_tunnels, access_mineral_storeroom)
 	alt_titles = list("Pathologist","Microbiologist")
 	minimal_player_age = 7
+	exp_requirements = 300
+	exp_type = EXP_TYPE_CREW
 	outfit = /datum/outfit/job/virologist
 
 /datum/outfit/job/virologist
@@ -245,6 +253,8 @@
 	access = list(access_paramedic, access_medical, access_sec_doors, access_maint_tunnels, access_external_airlocks, access_morgue)
 	minimal_access=list(access_paramedic, access_medical, access_sec_doors, access_maint_tunnels, access_external_airlocks, access_morgue)
 	minimal_player_age = 3
+	exp_requirements = 180
+	exp_type = EXP_TYPE_CREW
 	outfit = /datum/outfit/job/paramedic
 
 /datum/outfit/job/paramedic

code/game/jobs/job/science.dm

@@ -60,7 +60,8 @@
 	minimal_access = list(access_tox, access_tox_storage, access_research, access_xenobiology, access_xenoarch, access_maint_tunnels, access_mineral_storeroom)
 	alt_titles = list("Xenoarcheologist", "Anomalist", "Plasma Researcher", "Xenobiologist", "Chemical Researcher")
 	minimal_player_age = 3
-
+	exp_requirements = 300
+	exp_type = EXP_TYPE_CREW
 	// All science-y guys get bonuses for maxing out their tech.
 	required_objectives = list(
 		/datum/job_objective/further_research
@@ -97,6 +98,8 @@
 	minimal_access = list(access_robotics, access_tech_storage, access_morgue, access_research, access_maint_tunnels, access_mineral_storeroom) //As a job that handles so many corpses, it makes sense for them to have morgue access.
 	alt_titles = list("Biomechanical Engineer","Mechatronic Engineer")
 	minimal_player_age = 3
+	exp_requirements = 180
+	exp_type = EXP_TYPE_CREW
 
 	required_objectives = list(
 		/datum/job_objective/make_cyborg,