#293: log warning instead of assertion in Step for robustness

[hohwille]

Fixes #293:

• Replaced the assertion that a Step that already ended should not end again with a warning
• allow the Step to end again but avoid inconsistent transition from ERROR to SUCCESS
• changed LocalToolCommandlet to call postInstall() before step.success

[coveralls]

Pull Request Test Coverage Report for Build 8756340305

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 93 unchanged lines in 4 files lost coverage.
• Overall coverage increased (+0.2%) to 59.809%

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Files with Coverage Reduction	New Missed Lines	%
com/devonfw/tools/ide/tool/LocalToolCommandlet.java	1	77.45%
com/devonfw/tools/ide/step/Step.java	23	36.36%
com/devonfw/tools/ide/step/StepImpl.java	31	45.77%
com/devonfw/tools/ide/context/AbstractIdeContext.java	38	57.3%

Totals
Change from base Build 8756150707:	0.2%
Covered Lines:	4586
Relevant Lines:	7381

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💛 - Coveralls

[hohwille]

should be reviewed together with #282