[Bugfix][Oracle] Add ESCAPE when compiling LIKE

The oracle SQL documentation specifies that *there is no default escape character* and *the escape character, if specified, must be a character string of length 1*.
In expression the underscore (_) and the percent sign (%) can be escaped with the backslash (\). So in the Oracle Expression Compiler if the ESCAPE clause is not specified, the pattern is not valid.
To fix it, the Oracle Expression Compiler has to add the ESCAPE clause.

https://docs.oracle.com/cd/B12037_01/server.101/b10759/conditions016.htm

src/providers/oracle/qgsoracleexpressioncompiler.cpp

@@ -58,11 +58,11 @@ QgsSqlExpressionCompiler::Result QgsOracleExpressionCompiler::compileNode( const
             return Complete;
 
           case QgsExpressionNodeBinaryOperator::boILike:
-            result = QStringLiteral( "lower(%1) LIKE lower(%2)" ).arg( op1, op2 );
+            result = QStringLiteral( "lower(%1) LIKE lower(%2) ESCAPE '\\'" ).arg( op1, op2 );
             return Complete;
 
           case QgsExpressionNodeBinaryOperator::boNotILike:
-            result = QStringLiteral( "NOT lower(%1) LIKE lower(%2)" ).arg( op1, op2 );
+            result = QStringLiteral( "NOT lower(%1) LIKE lower(%2) ESCAPE '\\'" ).arg( op1, op2 );
             return Complete;
 
           case QgsExpressionNodeBinaryOperator::boIntDiv: