Implement throttling of test commands

### Contribution

- [ ] I'd be willing to implement this feature ([contributing guide](https://github.com/gemini-testing/hermione/blob/master/CONTRIBUTING.md))

### Describe the user story

When running tests locally, for instance, via devtools protocol they often run so fast you can't realise what's actually happening in the test.

### Describe the solution you'd like

To add something like `--throttle` parameter which takes amount of ms to wait before running each command in the test. This'd allow to watch the test run in "slow motion".

### Describe the drawbacks of your solution

One may accidentally commit this throttling to main branch/CI

### Describe alternatives you've considered

Recording videos, recording snapshots of test all solve similar issue, but the difference is that you can view them only the test has already ended. This feature allows to watch it live.