Split add and update test apis

[lampajr]

Changes proposed

• Split add and update APIs for Test creation and update
• Use POST for creation
• Use PUT for update
• Update the tests accordingly

Check List (Check all the applicable boxes)

• My code follows the code style of this project.
• My change requires changes to the documentation.
• I have updated the documentation accordingly.
• All new and existing tests passed.

[lampajr]

• Need to check the UI as this might have impacted how tests are updated