Add Unit tests for SafeProcessMap and OSHandler class

[NicolasFussberger]

Adds unit tests for SafeProcessMap and OSHandler classes.

To improve testability, two small changes are done:

• SafeProcessMap gets an ITerminationCallback interface instead of having a hard dependency on ProcessInfoNode class
• OSHandler makes use of baselibs score::os::SysWait for better testability of the wait() systemcall

[github-actions]

License Check Results

🚀 The license check job ran with the Bazel command:

bazel run --lockfile_mode=error //:license-check

Status: ⚠️ Needs Review

Click to expand output

[License Check Output]
Extracting Bazel installation...
Starting local Bazel server (8.4.2) and connecting to it...
INFO: Invocation ID: 1d6899a5-8cca-4906-afe6-b3244ef32f36
Computing main repo mapping: 
Computing main repo mapping: 
Loading: 
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    currently loading: 
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Analyzing: target //:license-check (1 packages loaded)
Analyzing: target //:license-check (1 packages loaded, 0 targets configured)
Analyzing: target //:license-check (1 packages loaded, 0 targets configured)

Analyzing: target //:license-check (33 packages loaded, 10 targets configured)

Analyzing: target //:license-check (84 packages loaded, 10 targets configured)

Analyzing: target //:license-check (132 packages loaded, 830 targets configured)

Analyzing: target //:license-check (145 packages loaded, 4513 targets configured)

Analyzing: target //:license-check (157 packages loaded, 8093 targets configured)

Analyzing: target //:license-check (157 packages loaded, 8094 targets configured)

Analyzing: target //:license-check (158 packages loaded, 8218 targets configured)

INFO: Analyzed target //:license-check (162 packages loaded, 10232 targets configured).
[1 / 1] no actions running
[14 / 16] [Prepa] JavaToolchainCompileBootClasspath external/rules_java+/toolchains/platformclasspath.jar
[15 / 16] Building license.check.license_check.jar (); 0s disk-cache, multiplex-worker
INFO: Found 1 target...
Target //:license.check.license_check up-to-date:
  bazel-bin/license.check.license_check
  bazel-bin/license.check.license_check.jar
INFO: Elapsed time: 21.741s, Critical Path: 2.43s
INFO: 16 processes: 12 internal, 3 processwrapper-sandbox, 1 worker.
INFO: Build completed successfully, 16 total actions
INFO: Running command line: bazel-bin/license.check.license_check ./formatted.txt <args omitted>
usage: org.eclipse.dash.licenses.cli.Main [-batch <int>] [-cd <url>]
       [-confidence <int>] [-ef <url>] [-excludeSources <sources>] [-help] [-lic
       <url>] [-project <shortname>] [-repo <url>] [-review] [-summary <file>]
       [-timeout <seconds>] [-token <token>]

[github-actions]

The created documentation from the pull request is available at: docu-html

[pahmann]

Approve this PR after independent review was conducted by subject matter expert missing committer status. Acting on behalf of the contributor.