Add config option `interval`

[GregoryAlbouy]

Description

We want the user to be able to do some basic load testing on its endpoints.
To achieve this we can provide an interval options to determine the interval between two requests.
Note that this shouldn't be compatible with concurrency != 1, so it also require a validation update.

Tasks

• Add RunnerOptions.Interval (time.Duration) to config.Config
• Update configfile CLI flags parsers accordingly
• Update config.Config.Validate: it must be invalid if interval != 0 && concurrency != 1 Update: perfectly compatible with concurrency != 1
• Implement the interval in requester.Requester.Run

Suggestions

Notes