#906 Add feature configurable intellij vm args

[jakozian]

This PR fixes #906

Implemented changes:

• Added ide variable to accept jvm options.
• Added functionality to create a custom .vmoptions file in the conf folder which is the referenced by the intellij env variable IDEA_VM_OPTIONS which extends or overwrites the defaul jvm options by intellij.
• Added variable to the variables.doc

---

Checklist for this PR

Make sure everything is checked before merging this PR. For further info please also see
our DoD.

• When running mvn clean test locally all tests pass and build is successful
• PR title is of the form #«issue-id»: «brief summary» (e.g. #921: fixed setup.bat). If no issue ID exists, title only.
• PR top-level comment summarizes what has been done and contains link to addressed issue(s)
• PR and issue(s) have suitable labels
• Issue is set to In Progress and assigned to you or there is no issue (might happen for very small PRs)
• You followed all coding conventions
• You have added the issue implemented by your PR in CHANGELOG.adoc unless issue is labeled
  with internal

[coveralls]

Coverage Report for CI Build 24404759772

Coverage increased (+0.05%) to 70.501%

Details

• Coverage increased (+0.05%) from the base build.
• Patch coverage: No coverable lines changed in this PR.
• 10 coverage regressions across 2 files.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

10 previously-covered lines in 2 files lost coverage.

File	Lines Losing Coverage	Coverage
com/devonfw/tools/ide/tool/intellij/Intellij.java	9	82.31%
com/devonfw/tools/ide/variable/IdeVariables.java	1	94.0%

---

Coverage Stats

Relevant Lines:	15111
Covered Lines:	11109
Line Coverage:	73.52%
Relevant Branches:	6720
Covered Branches:	4282
Branch Coverage:	63.72%
Branches in Coverage %:	Yes
Coverage Strength:	3.1 hits per line

---

💛 - Coveralls