Swift: Add a summary query for regex evals.

Author: geoffw0

swift/ql/src/queries/Summary/RegexEvals.ql

@@ -0,0 +1,15 @@
+/**
+ * @name Regular Expression Evaluations
+ * @description List all regular expression evaluations found in the database.
+ * @kind problem
+ * @problem.severity info
+ * @id swift/summary/regex-evals
+ * @tags summary
+ */
+
+import swift
+import codeql.swift.regex.Regex
+
+from RegexEval e
+select e,
+  "Regular expression evaluation with " + count(e.getARegex()).toString() + " associated regex(s)"