[gRPC] Expose the timestamp flag when starting a Monitor

[kittaakos]

Describe the request

As part of #2336, one can get the timestamp from the CLI. This is great, and IDE2 wants to use it.

Please add the timestamp property to the MonitorRequest. (Here is a PR that will change the same API: #2276).

As a pipedream, it would be great if the timestamp type could be boolean | string. When it's a string, it must be a valid date format string so that clients can change the output.

Describe the current behavior

There is no gRPC equivalent of monitor --timestamp

Arduino CLI version

5a4f48b

Operating system

macOS

Operating system version

13.5.2

Additional context

No response

Issue checklist

• I searched for previous requests in the issue tracker
• I verified the feature was still missing when using the nightly build
• My request contains all necessary details