Refactor SQL script support

This commit continues the work in the previous commit as follows:

 - Introduced an exception hierarchy for exceptions related to SQL
   scripts, with ScriptException as the base.

 - CannotReadScriptException and ScriptStatementFailedException now
   extend ScriptException.

 - Introduced ScriptParseException, used by ScriptUtils.splitSqlScript().

 - DatabasePopulatorUtils.execute() now explicitly throws a
   DataAccessException.

 - Polished Javadoc in ResourceDatabasePopulator.

 - Overhauled Javadoc in ScriptUtils and documented all constants.

 - Added missing @author tags for original authors in ScriptUtils and
   ScriptUtilsTests.

 - ScriptUtils.splitSqlScript() now asserts preconditions.

 - Deleted superfluous methods in ScriptUtils and changed method
   visibility to private or package private as appropriate.

 - Deleted the ScriptStatementExecutor introduced in the previous
   commit; ScriptUtils.executeSqlScript() now accepts a JDBC Connection;
   JdbcTestUtils, AbstractTransactionalJUnit4SpringContextTests, and
   AbstractTransactionalTestNGSpringContextTests now use
   DatabasePopulatorUtils to execute a ResourceDatabasePopulator instead
   of executing a script directly via ScriptUtils.

 - Introduced JdbcTestUtilsIntegrationTests.

Issue: SPR-9531

spring-test/src/test/resources/org/springframework/test/jdbc/data.sql

@@ -0,0 +1 @@
+INSERT INTO person VALUES('bob');

spring-test/src/test/resources/org/springframework/test/jdbc/schema.sql

@@ -0,0 +1,4 @@
+CREATE TABLE person (
+  name VARCHAR(20) NOT NULL,
+  PRIMARY KEY(name)
+);