feat(sfp-package): add support for unpackaged metadata in unlocked packages

[azlam-abdulsalam]

Add support for unpackaged metadata. This was removed as sfpowerscripts do parallel build of unlocked packages in individual working directory and
working directory didnt copy the unpackaged directory. Support is added to copy unpackaged directory
and copy the folder to appropriate working directory. sfdx-project.json is then aligned for
sucessful preparation of the package. The unpackaged is a package directory and it will be upto the
user to determine the behaviour during validate,prepare or deploy. This along with changes in #842
which will skip the directories which doesnt have package name or version number, but will get
still picked up during 'push'

fix #958

Checklist

All items have to be completed before a PR is merged

• Adhere to Contribution Guidelines
• Updates to Decision Records considered?
• Updates to documentation at DX@Scale Guide considered?
• Tested changes?
• Unit Tests new and existing passing locally?

[codecov-commenter]

Codecov Report

Merging #1056 (e92ff56) into develop (d0291e4) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #1056   +/-   ##
========================================
  Coverage    59.55%   59.55%           
========================================
  Files           52       52           
  Lines         1674     1674           
  Branches       357      357           
========================================
  Hits           997      997           
  Misses         634      634           
  Partials        43       43           

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