[Linux] `zip` package should be included as a dependency

[grynspan]

On Linux, Swift Testing uses the zip package/tool to compress directories when they are recorded as test attachments. We should make sure that it's included in the dependency list for supported Linux distros. (In particular, it's not included by default on Debian which leads to test failures there.)

[cmcgee1024]

There are multiple places where this dependency should be added at the moment, such as the swift.org website, and the docker images. These changes should all be coordinated so that there isn't confusion.