Add Support for Retry in WP CLI Core Download Command

[abhi3315]

Description

This PR supports a retry mechanism in the WP CLI core download command. With the addition of --retry= and --retry-delay= flags, users can now specify the number of retry attempts and the delay between retries in case the download fails due to network issues or other transient errors.

Features Added:

• The --retry=<retry> flag allows users to specify the number of retry attempts in case of download failure. The default value is set to 0.
• The --retry-delay=<delay> flag allows users to specify the delay (in seconds) between retry attempts. The default delay is set to 5 seconds.

Usage Examples:

• wp core download --retry=5 --retry-delay=10 - Downloads WordPress core with 5 retry attempts and a delay of 10 seconds between each attempt.
• wp core download --retry=3 - Downloads WordPress core with 3 retry attempts using the default delay of 5 seconds between each attempt.

Issue: https://github.com/wp-cli/core-command/issues/155

[schlessera]

We do have a recurring need for retries in several places, so I think it would make sense to add the capability for retries to Utils\http_request(). It has an $options argument that we can extend to support retry semantics.

The only thing to keep aware of is that it already contains a retry mechanism for retrying failed verified requests in an unverified way. The logic will probably end up looking more complex that it should because of that.