Implement coercion of numeric types for ascription and arithmetic (off by default)

Signed-off-by: Nick Cameron <nrc@ncameron.org>

rust/kcl-lib/tests/fillet-and-shell/program_memory.snap

@@ -307,7 +307,13 @@ description: Variables in memory after executing fillet-and-shell.kcl
     "type": "Number",
     "value": 73.0,
     "ty": {
-      "type": "Unknown"
+      "type": "Default",
+      "len": {
+        "type": "Mm"
+      },
+      "angle": {
+        "type": "Degrees"
+      }
     }
   },
   "caseThickness": {
@@ -327,7 +333,13 @@ description: Variables in memory after executing fillet-and-shell.kcl
     "type": "Number",
     "value": 38.0,
     "ty": {
-      "type": "Unknown"
+      "type": "Default",
+      "len": {
+        "type": "Mm"
+      },
+      "angle": {
+        "type": "Degrees"
+      }
     }
   },
   "connectorPadding": {
@@ -367,7 +379,13 @@ description: Variables in memory after executing fillet-and-shell.kcl
     "type": "Number",
     "value": 58.0,
     "ty": {
-      "type": "Unknown"
+      "type": "Default",
+      "len": {
+        "type": "Mm"
+      },
+      "angle": {
+        "type": "Degrees"
+      }
     }
   },
   "m25Screw": {