希望增加一列拆成多行的函数

**Describe the feature you'd like**
我的数据是这样的：“1:0.31234|3:0.532|56:0.99|8:0.345”
希望有一个函数，类似于explode，能够按照指定分隔符，将一列拆分成多行。

Look for existing SQL function implementations in the codebase, particularly string manipulation and row expansion functions like 'explode'. Understand how new UDFs are added to OpenMLDB's SQL engine. The feature requires parsing a string column by a delimiter (like '|' and possibly ':') and transforming one row into multiple rows. Check test files for similar functionality to see the expected interface and behavior.

Escrito por el modelo de indexación a partir del texto del issue.