Fix FlatBuffers field names to use lowercase snake_case in lm_flatcfg.fbs

[shegazyy]

The FlatBuffers compiler warns when field names do not follow lowercase snake_case convention. Rename all non-conforming fields in lm_flatcfg.fbs (e.g. versionMajor -> version_major, startupConfig -> startup_config). Binary compatibility is preserved because field IDs (id:N) are unchanged.

Update configuration_manager.cpp to use the new generated accessor names, and update the expected JSON output fixtures in the config_mapping tests.

Closes #288

[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 (8.6.0) and connecting to it...
INFO: Invocation ID: 6e48384d-f211-40e7-83db-96d2cbc966bf
Computing main repo mapping: 
Computing main repo mapping: 
Loading: 
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Analyzing: target //:license-check (1 packages loaded, 0 targets configured)
Analyzing: target //:license-check (1 packages loaded, 0 targets configured)

Analyzing: target //:license-check (34 packages loaded, 10 targets configured)

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

Analyzing: target //:license-check (143 packages loaded, 1123 targets configured)

Analyzing: target //:license-check (151 packages loaded, 5484 targets configured)

Analyzing: target //:license-check (161 packages loaded, 5547 targets configured)

Analyzing: target //:license-check (161 packages loaded, 5547 targets configured)

Analyzing: target //:license-check (162 packages loaded, 5547 targets configured)

Analyzing: target //:license-check (164 packages loaded, 7434 targets configured)

Analyzing: target //:license-check (164 packages loaded, 7434 targets configured)

Analyzing: target //:license-check (167 packages loaded, 10275 targets configured)

Analyzing: target //:license-check (168 packages loaded, 10283 targets configured)

Analyzing: target //:license-check (168 packages loaded, 10283 targets configured)

Analyzing: target //:license-check (168 packages loaded, 10283 targets configured)

Analyzing: target //:license-check (169 packages loaded, 10283 targets configured)

INFO: Analyzed target //:license-check (169 packages loaded, 10409 targets configured).
[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: 28.709s, Critical Path: 2.64s
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