Add feature to shift fragility by a certain given percentage

[pramodit13]

Add a function shift_fragility(fragilityCurveSet, percent), which

• takes the json file for mapping,
• extracts the fragility sets,
• extracts parameters, "expression" from the fragility and,
• shifts the fragility with the above function by the given percentage
• replaces the expressions with the new updated expression and substitute it back to the modified_fragilityCurveSet with copy.deepcopy(fragilityCurveSet) and saves the new jsons to the local disk or upload to get id.
• create newMappingSet from the new fragility sets by copying back to the original mapping json
• store locally or create id (provide options)