[READY] Upgrade to LLVM 18.1.0

[bstaletic]

Latest clangd does not provide a fixit to change

struct s {
        ~s();
};
s::~s() {}

to

struct s {
        ~s();
};
s::~s() = default;

Otherwise, things seem to work.

---

This change is 

[codecov[bot]]

Codecov Report

Merging #1737 (05000b7) into master (b63d2e8) will not change coverage. The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1737   +/-   ##
=======================================
  Coverage   95.46%   95.46%           
=======================================
  Files          83       83           
  Lines        8201     8201           
  Branches      163      163           
=======================================
  Hits         7829     7829           
  Misses        322      322           
  Partials       50       50           

[bstaletic]

Closing for now. Let's wait until https://github.com/llvm/llvm-project/issues/84168 is resolved.