Ignore negations not implemented

[kf6kjg]

In the code the negations are skipped. This misses a critical feature in an ignore file: how to ignore all except some.

Use case: I want to drop everything in the locutus module except the datetime files I'm interested in:

node_modules/locutus/**
!node_modules/locutus/php/datetime/**/*.js

Since the current code skips all negated patterns I wind up not having anything in the locutus folder.

The following works in the serverless.yaml file, per the documentation:

package:
  patterns:
    - "!node_modules/locutus/**"
    - "node_modules/locutus/php/datetime/**/*.js"

Thus there's a workaround: handle most ignores in the .slsignore file, but anything you need negations for use the serverless.yaml file.

[kf6kjg]

Possible solution would be to switch to this.serverless.package.patterns introduced in serverless/serverless#8581 and then simply invert the negation as an ignore file has inverse grammar from the patterns: aka !asdf becomes asdf and qwerty becomes !querty.