Support multi-line comments in SQL scripts

Prior to this commit neither ResourceDatabasePopulator nor
JdbcTestUtils properly supported multi-line comments (e.g., /* ... */).
Secondarily there has developed a significant amount of code
duplication in these two classes that has led to maintenance issues
over the years.

This commit addresses these issues as follows:

 - Common code has been extracted from ResourceDatabasePopulator and
   JdbcTestUtils and moved to a new ScriptUtils class in the
   spring-jdbc module.

 - Relevant test cases have been migrated from JdbcTestUtilsTests to
   ScriptUtilsTests.

 - ScriptUtils.splitSqlScript() has been modified to ignore multi-line
   comments in scripts during processing.

 - ResourceDatabasePopulator supports configuration of the start and end
   delimiters for multi-line (block) comments.

 - A new test case was added to ScriptUtilsTests for the new multi-line
   comment support.

Issue: SPR-9531
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