Add `--recreate-db` option to `install-wp-tests.sh`

[vcanales]

This adds a --recreate-db option to remove the need for user input when running the script for confirming database recreation, helpful when it is run in a CI context, such as a part of a GitHub Action. The command can be safely run without flags, and it will respect the order of the other options.

Also, refactors the help message and when it is printed.