test: migrate 700_e2e rows to corpus fixtures; retire the carrier

136 rows migrated, 0 already owned, 3 wwstage-failing rows held out.

test/wcc/data/r700_enum_auto/case.ww

@@ -0,0 +1,5 @@
+//ww:run-exit 2
+// Migrated from 700_e2e row 115.
+package main;
+type color = enum { RED, GREEN, BLUE };
+fn main() i32 = { return color.BLUE as i32; };