convert io pointer value into client facing value instead of hash

[Boyuan-Deng]

This PR:

• originally, the input & output IOPointer in componentRun retrieved from history class are storing a hash value of the value
• now, the original input & output is stored as a original-content field of the input & output IOPointer

Test:

run python examples/io_pointer_load_test.py under mltrace directory, you should expect to see no difference in dataframe