Add error handling for jsonPathString UDF when jsonPath is non-existent

If you use "non default value" version i.e **jsonPathString(Object object, String jsonPath)** then there is no error handling in case jsonPath doesn't exist and will cause data ingestion to fail. Need to return null in such scenarios so data ingestion is not impacted.

Similar to above function other functions for e.g jsonPathDouble() etc. need to be updated as well.

cc @npawar

Start by locating the jsonPathString(Object object, String jsonPath) UDF and the related jsonPathDouble() and other jsonPath functions. Check how they handle a non-existent jsonPath, then verify that each affected function returns null so ingestion is not interrupted.

Written by the indexing model from the issue text.