Be able to stop code execution

[nathanfallet]

Describe the bug
When some never ending code is executed, we are unable to stop its execution in the top level

To Reproduce
Steps to reproduce the behavior:

1. Write some never ending code
2. Execute it

Example code:

let a n =
  let b = ref 0 in
  while n <> 0 do
    b := !b + 1
  done;;
a 1;;

Expected behavior
Add a way to stop code execution

Screenshots

Smartphone (please complete the following information):

• Device: iPhone X
• OS: iOS 14.4.2
• Version: 1.1.1

Additional context

[nathanfallet]

With #21, it's now possible to reload the console to stop code execution. Now we need to see if we add a stop button to replace the play button while executing, or only use the reload button.