fix tests (+memfs +jest)

[maiconcarraro]

@ibrahimkarahan I noticed the last checks are failing, and it could be the reason to not release a new version yet, so sending this PR to fix the tests and try to help release a new version soon - a lot of devs from PWABuilder will benefit from this.

Some tests are using mock-fs which has some incompatibility at the moment: tschaub/mock-fs#384 and that's the cause for these errors: https://github.com/GoogleChromeLabs/bubblewrap/actions/runs/9993866664/job/27622289533

Module mocking with jasmine is a little bit tricky, but very easy with jest, so while doing the replacement of mock-fs to memfs I also migrated to jest (and ts-jest), I know it can be controversial... I couldn't make it work well with jasmine... I did make sure to match the previous expected result, including the customization for some describe errors.

Before (from CI):

After:

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