Add ability to deprecate packages

[nilFinx]

First thing that this should be used on is creationix/coro-tls, as it appears to be luvit/tls, but ancient. Few other packages might want the same treatment too.

[truemedian]

Anything related to modifying existing packages is unlikely to stick. The design of lit is such that once a package is published, it becomes immutable.

Not that modifying an existing package is impossible, but it would require changing the package, resigning it, and then publishing it and overwriting the existing reference to that version.

[Bilal2453]

obsolete is already a thing: https://github.com/luvit/lit/wiki/Package-Metadata#metaobsolete

[nilFinx]

Oh, nice. Closing this then.
@creationix, do you mind labelingsome stuff you made as obsolete? For example, creationix/tls appears to be luvit/lls but ancient.