[milo] Add BuildSummary and common models.

milo/api/resp/verbosity_string.go

+// Code generated by "stringer -type=Verbosity"; DO NOT EDIT.
+
+package resp
+
+import "fmt"
+
+const _Verbosity_name = "NormalHiddenInteresting"
+
+var _Verbosity_index = [...]uint8{0, 6, 12, 23}
+
+func (i Verbosity) String() string {
+        if i < 0 || i >= Verbosity(len(_Verbosity_index)-1) {
+                return fmt.Sprintf("Verbosity(%d)", i)
+        }
+        return _Verbosity_name[_Verbosity_index[i]:_Verbosity_index[i+1]]
+}