NETSCRIPT: Add the 'cat' method to 'ns.singularity'

[NagaOuroboros]

Motivation

While .lit files are easy to copy onto the 'home' server, doing so clutters up the root directory, and will only create more clutter as new .lit files get added in the future. As a first step to managing this, I've implemented the functionality of the cat terminal command as a method available on the ns.singularity namespace.

This addition should let players write their own 'remote file viewer' scripts once they've gotten SF4.

Scope

This PR only adds the new method itself, which is simply a 1:1 feature-for-feature implementation of the terminal equivalent. No new behaviors are added.

New API Method

ns.singularity.cat(filename) - Displays the content of a file on the currently connected server

Considerations

• The RAM cost of the method is currently set at 0.5 before the SF4 multipliers. I would argue for lower, perhaps even 0.1, but I feel 0.5 is a reasonable upper limit. There is no gameplay advantage to this method—it is purely a quality of life addition—so I do not feel it deserves to be any higher, especially as it will often be used in conjunction with ns.singularity.connect.

[NagaOuroboros]

Refactor

Changed the implementation to simply hook directly into the terminal command's logic. Also added the missing check for the player owning SF4.