baker improve retry event

What

This MR aims to improve the retry function used in the baker by allowing errors to be used in the message to print and by allowing by default an unlimited number of retries.

Why

to be able to call retry with

      Utils.retry
        ~emit:Events.(emit toto)
        ~msg:(fun errs ->
          Format.asprintf
            "unable to call f.@, %a"
            pp_print_trace
            errs)
        (fun () ->
          (f ...

How

Manually testing the MR

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR