Smart assertion - Allow updating the Smart Assertion without loosing what is already configured

For the Smart Assertion tool to be useful, it must be possible to update current values without losing what is already configured. Currently if a piece of data changes, you have to reload the whole response, which causes the loss of all the previous configuration. Moreover, this makes cloning completely useless because if we clone a test, the configured Smart Assertion doesn't work anymore. You need to reload everything. When you have a lot of elements in your JSON response, and you assert the values against a data source, it's a lot of wasting time redoing what you have already done previously.