added various participant types/icons

src/consts.typ

@@ -1,5 +1,16 @@
 #let Y-SPACE = 10
-#let PAR-PAD = (5pt, 3pt)
 #let PAR-SPACE = 10
 #let COMMENT-PAD = 8
-#let LIFELINE-W = 10
+#let LIFELINE-W = 10
+
+#let SYM-GAP = 5
+#let PAR-PAD = (5pt, 3pt)
+#let ACTOR-WIDTH = 20
+#let BOUNDARY-HEIGHT = 20
+#let CONTROL-HEIGHT = 20
+#let ENTITY-HEIGHT = 20
+#let DATABASE-WIDTH = 24
+#let COLLECTIONS-PAD = (5pt, 3pt)
+#let COLLECTIONS-DX = 3
+#let COLLECTIONS-DY = 3
+#let QUEUE-PAD = (5pt, 3pt)