add file paths to updates

[sigmaSd]

I think it used to be the case, but it got removed at some point ?

when running molt (without a file) I can't tell on which file these updates are present

[hasundue]

It has been changed to be an optional behavior by --referrer since 0.19.0. The reasons behind are:

• They seem redundant and unnecessary when dependencies are manifested in deno.json
• They may reduce readability of outputs when you have many dependency sources

But I am not quite confident with the decision or the specification (including the name of the option), and open to your opinion to ideas.

The next release (0.20.0) should include a support of Deno 2.0 and some breaking changes, so it may be a good chance to put additional ones.