[MSHADE-196] Must not attempt to unzip unfamiliar dependency type

**[Markus Karg](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=mkarg)** opened **[MSHADE-196](https://issues.apache.org/jira/browse/MSHADE-196?redirect=false)** and commented

When adding dependencies to rather unconventional package types, like "dll" or "pdf", we noticed that the share plugin by default tries to unzip them. This is weird, as obviously this attempt will fail in almost any case. A user is forced to add explicit exceptions, which is tedious, error prone, and breaks CoC.

The solution is rather obvious: The shade plugin must only unzip those package types which it is familiar with. This namely is e. g. JAR, ZIP, BZIP, GZIP etc. but certainly not anything unknown.

The result of this change will be a simplification of the pom.xml, and shade plugin's behaviour will be more like a user expects it to work: Don't touch unkown stuff!

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**Affects:** 2.3

Start by locating the shade plugin's dependency unpacking logic and existing tests for package-type handling. Reproduce the case with an unfamiliar dependency such as a DLL or PDF, then verify that recognized archive types are still unpacked while unknown types are left untouched.

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