Support single quotes nested in double quotes in SQL scripts

Some databases such as Oracle permit double quoted column aliases that
contain case-sensitive characters, single quotes, and other special
characters; however, prior to this commit, SqlScripts interpreted a
single quote nested within double quotes as the start of a string
literal resulting in improper parsing.

This commit addresses this issue by ensuring that double quoted strings
such as column aliases are properly parsed even when containing single
quotes.

Issue: SPR-13218

spring-jdbc/src/test/resources/org/springframework/jdbc/datasource/init/users-data-with-single-quotes-nested-in-double-quotes.sql

@@ -0,0 +1,7 @@
+INSERT INTO users(first_name, last_name) VALUES('Juergen', 'Hoeller');
+
+-- The following is not actually used; we just want to ensure that it does not
+-- result in a parsing exception due to the nested single quote.
+SELECT last_name AS "Juergen's Last Name" FROM users WHERE last_name='Hoeller';
+
+INSERT INTO users(first_name, last_name) values('Sam', 'Brannen');