Support correct execution status for native REPL

[anthonykim1]

In the native REPL, we should correctly mark the execution status as either failure (red x mark) or success (green check mark) depending on the output of the user's code execution.

For example, if import failed, we should not only tell the uiser that the import failed but also mark the cell of the native REPL to show red x mark failure status.

[karthiknadig]

Verification Steps:

1. Run some code in python REPL.
2. If it succeeds it should have a tick mark, else it should show failed status

[rzhao271]

Failing commands are getting checkmarks too