#351: prevent environment variables from other project causing side-effects

[hohwille]

This PR fixes #351.

Implemented changes:

• implemented Avoid inheriting environment variables from other IDEasy project if switched in the same shell session #351
• ignore all environment properties relevant to IDEasy except for PATH, HOME, and IDE_ROOT
• added test
• improved test-infrastructure to behave more realistic using EnvironmentVariablesSystem that was otherwise mocked by a different class.

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• When running mvn clean test locally all tests pass and build is successful
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[coveralls]

Pull Request Test Coverage Report for Build 15217001708

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.08%) to 67.878%

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Totals
Change from base Build 15216934814:	0.08%
Covered Lines:	8073
Relevant Lines:	11491

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💛 - Coveralls

[jan-vcapgemini]

LGTM. Tested with a local graalvm native image.
Before:

After:

[jan-vcapgemini]

I've tested these changes on Windows, Linux and Mac and it worked on all systems.