#280: configure maven properly

[mvomiero]

Fixes: #280

There is a related PR to ide-settings that renames the devon folder to ide, as suggested by @hohwille .
devonfw/ide-settings#45

Note: the configuration will properly work just if the settings are properly updated (or if locally the devon folder in settings is manually renamed to ide)

[coveralls]

Pull Request Test Coverage Report for Build 9030688796

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 184 unchanged lines in 5 files lost coverage.
• Overall coverage decreased (-0.5%) to 59.352%

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Files with Coverage Reduction	New Missed Lines	%
com/devonfw/tools/ide/context/GitContext.java	5	0.0%
com/devonfw/tools/ide/context/IdeContext.java	11	47.22%
com/devonfw/tools/ide/context/GitContextImpl.java	30	48.63%
com/devonfw/tools/ide/context/AbstractIdeContext.java	63	56.91%
com/devonfw/tools/ide/tool/mvn/Mvn.java	75	5.0%

Totals
Change from base Build 9001644591:	-0.5%
Covered Lines:	4611
Relevant Lines:	7485

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💛 - Coveralls

[jan-vcapgemini]

Thanks for your addition, finally we can use maven properly :)
I've added some small CR's and I'd suggest to add tests for these features in a new PR as this feature is quite important and needs to be merged asap.

[jan-vcapgemini]

Thanks for your adjustments. I've added some small suggestions, but think this can go into review now.

[mvomiero]

• I used this PR to update the variables concerning maven in the documentation (variables.adoc) as well. MAVEN_ARGS replaces MAVEN_OPTS as alredy implemented in #212: m2 repo settings as MAVEN_ARGS  #275
• NOTE: because of the high priority of this PR, unit tests for mvn will be properly developed in a different PR that will follow up.

[hohwille]

@mvomiero thank you for your PR. Nice work, looks good. 👍
However, I left some review comments for rework to make everything consistent.
Please have a look and rework the commented spots then we can merge.