[CURA-11359] sanitize code

[wawanbreton]

The main purpose of this PR is to remove all the compilation warnings issued when using the enable_extensive_warnings option is set. On the currant master branch, there are 16000+ warnings which makes it completely impossible to use them relevantly.

Most notable changes made:

• Renaming of geometry classes to make sure that the used variables types are clear and consistent all over the code. This helps removing the warnings.
• Renaming of most members variables with a _ as suffix to diferentiate them from local variables
• Removed some dead classes (ProximityPointLink, ClientSocket).
• Updated spdlog/fmt versions to suppress some warnings coming from them. This comes wih the same update for synsepalum-dulcificum and also for gradual flow plugin

Some parts of the code have become less readable, especially because of the numbers conversions. This emphasizes a global code issue that various types are used and mixed together, which should not happen. This should be fixed along the way.

[github-actions[bot]]

Unit Test Results

26 tests  ±0   26 :heavy_check_mark: ±0   6s :stopwatch: ±0s   1 suites ±0     0 :zzz: ±0    1 files   ±0     0 :x: ±0 

Results for commit fad6bd5a. ± Comparison against base commit 537f1c2f.

:recycle: This comment has been updated with latest results.

[casperlamboo]

Also, there are some merge conflicts