Add list command

[xeno010]

Add new list command: php artisan backup:list

List all backups

[freekmurze]

Thanks for your contribution. Awesome feature. I'll review it in detail in the coming days.

[freekmurze]

Some remarks on the output:

• the "create at" column should be renamed "Created at"
• it think it's better to output just one table for all backups. There should be a column named "Filesystem" that list the name of the filesystem the backup is saved on.
• the "Expired in" column should be replace by and "Age" column that shows the age in days.

In your code you use several abbreviations like $col and $v. Please use full variable names, the are easier to read.

Could you make these changes? Then I'll pull.

[xeno010]

Thank you very much for your feedback.

I have done all the points.

Here a new screenshot

[freekmurze]

Thanks!

[freekmurze]

This code of this PR is included in version 2.10.0.