Ghost role probability (#9752)

* Ghost role probability

* give it to regular ticks/bears too

Content.Server/Ghost/Roles/Components/GhostRoleComponent.cs

@@ -18,6 +18,13 @@ namespace Content.Server.Ghost.Roles.Components
         [ViewVariables(VVAccess.ReadWrite)] [DataField("makeSentient")]
         protected bool MakeSentient = true;
 
+        /// <summary>
+        ///     The probability that this ghost role will be available after init.
+        ///     Used mostly for takeover roles that want some probability of being takeover, but not 100%.
+        /// </summary>
+        [DataField("prob")]
+        public float Probability = 1f;
+
         // We do this so updating RoleName and RoleDescription in VV updates the open EUIs.
 
         [ViewVariables(VVAccess.ReadWrite)]