Add cmake package information

[werwurm]

Add cmake package information generation to make it easier to use for downstream users.

[github-actions]

LCOV of commit 7a0306f during lcov-test-coverage-report #50

Summary coverage rate:
  lines......: 96.1% (2420 of 2517 lines)
  functions..: 99.5% (194 of 195 functions)
  branches...: 87.3% (1373 of 1573 branches)

Files changed coverage rate: n/a

[Copilot]

Pull request overview

This pull request adds CMake package configuration to enable LibNat20 to be consumed by downstream projects using CMake's find_package() mechanism. The changes implement proper CMake export targets and installation rules for the library.

Changes:

• Added LibNat20Config.cmake.in template for CMake package configuration
• Modified target source visibility from INTERFACE to PRIVATE for all library targets
• Updated include directories to use generator expressions for build/install interface distinction
• Added install() commands for library targets, headers, and CMake configuration files

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
cmake/LibNat20Config.cmake.in	New CMake package configuration template that enables find_package(LibNat20) support
CMakeLists.txt	Updated library targets with proper generator expressions, added install rules for targets and headers, and configured CMake package exports
.github/license-check/license-config.json	Added cmake.in pattern to license check configuration

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 6 comments.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

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[seidelrj]

Not a cmake expert, but this looks reasonable.