Unpack zipped crates into unique temporary folder

[Code42Cate]

No description provided.

[Pfeil]

This is a workaround around issue #56 for the usage with a service offering ro-crate-java as a REST API.

[Pfeil]

TODO (copied from #56 and extended)

• should be unpacked in subfolder so different imported crates do not interfere
  • Subfolders (e.g. .tmp-ro-crate-java-extracted_cratefile.zip) beside the zip files would be easy to associate etc, but we would mess around in possibly synchronized or otherwise managed directories.
  • The current state uses the folder of where ro-crate-java is running from and stores it in ./temp/$UUID and works. This basically fulfills this task.
  • Suggestion: Use ./.tmp/ro-crate-java/zip-extraction/$UUID-filename.zip or something similar? Optional, take a parameter for the strategy to set up another directory.
• the content should be removed at some point, currently it is "on JVM exit". This is not really a nice solution, because the library may be included into a server application which may run for longer terms.
  • The question is who is responsible for deletion.
  • The folder needs to live as long as any crate instance which is created by it.
  • The readers will usually live shorter, so they can not manage the folder.
  • The crate may be cloned (creating a builder, then create a new crate, or any other java magic), so it also cannot do it.
  • Suggestion: we manage it by restarts, but the user may choose to manage this situation manually be retrieving information about the location.
  • In the future, we could provide a helper class to make this easier somehow. But I do not see how we can make this being fully managed automatically in the background.

[coveralls]

Pull Request Test Coverage Report for Build #258

Details

• 24 of 25 (96.0%) changed or added relevant lines in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.001%) to 90.688%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/main/java/edu/kit/datamanager/ro_crate/reader/ZipReader.java	24	25	96.0%

Files with Coverage Reduction	New Missed Lines	%
src/main/java/edu/kit/datamanager/ro_crate/reader/ZipReader.java	1	80.56%

Totals
Change from base Build #253:	0.001%
Covered Lines:	1607
Relevant Lines:	1772

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💛 - Coveralls

[Pfeil]

I kept the idea but added some customization possibility and changed the path. Thanks, @Code42Cate !