fix: Change unit tests floating point type to double and add a precision argument to output streams

[boxanm]

Description

The order of floating-point operations led to different results between these debug and release builds on ARM64.
This was probably due to different optimizations done by the compiler.
I changed the floating-point precision of all tests to double, which solved the failed transformation tests.
As a side task, I also had to add a precision argument to all Point cloud save functions to keep IO utests from failing.

Summary:

Fixes #556

Changes and type of changes (quick overview):

• Change the floating-point precision of all tests to double
• Add a precision argument to all Point cloud save functions

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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 README.md #Contributing
  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
• [ x 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 type
  • Types: feat fix docs style refactor perf test build ci chore revert
  • Breaking changes: <type>!
  • Reference:
    see commit_msg_reference.md
    in the repository root for details

[simonpierredeschenes]

Good job!

[sonarqubecloud]

Quality Gate passed

The SonarCloud Quality Gate passed, but some issues were introduced.

3 New issues
0 Security Hotspots
No data about Coverage
2.5% Duplication on New Code

See analysis details on SonarCloud