build: support meson build system

[mochaaP]

CMake feature parity:

• [x] Export meson target
• [ ] Export meson c++20 modules target
• [ ] Export cmake target
• [x] Installing headers
• [x] Googletest support
• [x] Freestanding tests
• [ ] Modules tests
• [x] Google Benchmark support
• [x] Extract examples from docs

Extra features:

• [x] Export pkgconfig target
• [x] clang-format support
• [x] Make fmtlib optional when building examples
• [x] Install documents to docdir

Tested on Fedora Linux 44 (gcc/clang/msvc-wine + ninja) and Windows 10 22H2 (msvc + vs2022).

[mochaaP]

@microsoft-github-policy-service agree

[mochaaP]

Thank you for the extensive review. I will work on the changes later.