Add file-level scanner for Linux kernel module (.ko) metadata

[OctavioValdiviaMendoza]

Fixes #625

This PR adds file-level scanning of metadata embedded in compiled Linux Kernel Module (.ko) files.

Implementation

A new LinuxKernelModuleScanner is implemented in scancode/plugin_lkm.py using ScanCode's file-level ScanPlugin architecture.

The scanner:

• Is enabled with the --lkm option.
• Uses pyelftools to open .ko files as ELF files.
• Locates the .modinfo ELF section.
• Parses its NUL-terminated key=value entries.
• Preserves repeated fields such as author, alias, and firmware as lists.
• Stores the extracted metadata in the file Resource's linux_kernel_module attribute.
• Normalizes the .modinfo depends value into a simple list of required kernel-module names.

For example:

{
  "linux_kernel_module": {
    "license": ["GPL"],
    "author": ["Example Author"],
    "depends": ["video", "backlight"]
  }
}

Tests

Test coverage includes:

• .modinfo extraction.
• Repeated metadata values.
• Required module-name parsing.
• Unrelated files.
• Invalid ELF files.
• Plugin enablement and Resource attribute declaration.
• End-to-end --lkm output.
• Verification that no package_data is created.

Tasks

• Reviewed contribution guidelines
• PR is descriptively titled 📑 and links the original issue above 🔗
• Tests pass
• Commits are in a uniquely named feature branch and have no merge conflicts 📁
• Updated CHANGELOG.rst (if applicable)
• Updated documentation pages (if applicable)