#218: add possibility to start a command in a new window with the process builder

[samuelkos17]

This PR fixes #218

Implemented changes:

• Added a new ProcessMode#BACKGROUND_NEW_WINDOW mode that starts a command in a new terminal window while detaching it from the parent process.
• Implemented platform-specific new-window command builders in ProcessContextImpl:
  • Linux: Detects available terminal emulators (gnome-terminal, konsole, xfce4-terminal, tilix, alacritty, xterm, x-terminal-emulator) and uses the correct flag syntax for each, with a disown fallback when no terminal emulator is available.
  • macOS: Uses osascript to launch a new Terminal.app or iTerm2 window via AppleScript.
  • Windows: Uses cmd.exe /c start to open a new CMD window.
• Added launchesNewWindow() method to ProcessMode to check whether the mode should launch a process in a new window.
• Updated isBackground() to include the new BACKGROUND_NEW_WINDOW mode.
• Added comprehensive tests in BackgroundNewWindowTest.java:
  • Structural (mock-based) tests for each platform verifying the generated command shape.
  • E2E tests for each platform using a marker-file polling approach to verify the subprocess actually executes.
  • Windows/macOS E2E tests skip in CI (windows would leak in headless CI runners); Linux E2E runs in CI via the disown fallback.

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Testing instructions

1. Run mvn clean test — all tests should pass, including the 10 new tests in BackgroundNewWindowTest.java.
2. Pay special attention to the E2E tests on your platform:
   • Windows: backgroundNewWindowShouldActuallyExecuteViaStartOnWindows — observe a new CMD window opening.
   • macOS: backgroundNewWindowShouldActuallyExecuteViaOsascriptOnMac — observe a new Terminal.app (or iTerm2) window opening.
   • Linux: backgroundNewWindowShouldActuallyExecuteOnLinux — observe a new terminal window opening (if a desktop environment is available), or the test passing via the disown fallback in headless environments.
   • These E2E tests are opening new windows that might not close by themselves, this is intentional and made so that we can verify that a new window opens on each of the three OS. Before merging this I intend to either change or completly remove them since we don't want to have terminal windows opening on our local dev environments every time we run tests. (I would be happy for suggestions on how to change them)

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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.
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  with internal
• You have formulated clear instructions on how to test your contribution under "Testing instructions"

[coveralls]

Coverage Report for CI Build 30622595516

Coverage decreased (-0.1%) to 72.527%

Details

• Coverage decreased (-0.1%) from the base build.
• Patch coverage: No coverable lines changed in this PR.
• 72 coverage regressions across 2 files.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

72 previously-covered lines in 2 files lost coverage.

File	Lines Losing Coverage	Coverage
com/devonfw/tools/ide/process/ProcessContextImpl.java	69	68.85%
com/devonfw/tools/ide/process/ProcessMode.java	3	91.43%

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Coverage Stats

Relevant Lines:	17357
Covered Lines:	13123
Line Coverage:	75.61%
Relevant Branches:	7697
Covered Branches:	5048
Branch Coverage:	65.58%
Branches in Coverage %:	Yes
Coverage Strength:	3.21 hits per line

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💛 - Coveralls