[MASSEMBLY-1013] Remove custom SAR UnArchiver

[slawekjaranowski]

It is implemented by newer plexus-archiver

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[elharo]

I assume this is fine though I'm missing context on it. The linked bug doesn't explain this specifically. What is "SAR"?

[slawekjaranowski]

SAR is a type of archive, but never mind what it is - it is implemented in https://github.com/codehaus-plexus/plexus-archiver/tree/master/src/main/java/org/codehaus/plexus/archiver/sar
So I remove as duplicated code.