Replace boost::timer with std::chrono::steady_clock

[boxanm]

Description

Summary:

This PR addresses #597 and the deprecation of boost::timer when not using POSIX timers.
It also adds a CMake variable DISABLE_POSIX_TIMERS to control whether the POSIX timers or std::chrono::steady_clock are used. Finally there is a simple example script showing how to use PointMatcherSupport::timer in code.

Checklist:

Code related

• I have made corresponding changes to the documentation
  (i.e.: function, class, script header, README.md)
• I have commented hard-to-understand code
• I have added tests that prove my fix is effective or that my feature works
• All tests pass locally with my changes
  (Check contributing_instructions.md for local testing procedure using libpointmatcher-build-system)

PR creation related

• My pull request base ref branch is set to the develop branch
  (the build-system won't be triggered otherwise)
• My pull request branch is up-to-date with the develop branch
  (the build-system will reject it otherwise)

PR description related

• I have included a quick summary of the changes
• I have indicated the related issue's id with # <issue-id> if changes are of type fix
• I have included a high-level list of changes and their corresponding types
  (See commit_msg_reference.md for details)

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[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud