Fix autotools build

[mszabo-wikia]

The OSS autotools build has been nonfunctional for about a year. While #449 would be a better long-term approach to fixing the build since it would also bring it in sync with other Meta OSS projects and enable testing in CI, fixing the existing build until there's movement on that front would at least provide a signal on whether the OSS version is buildable at all.

So:

• Introduce new Ubuntu 24.04 build files and use them in CI. I'll remove build files, Dockerfiles etc. for ancient Ubuntu and CentOS versions in a followup PR.
• Pin fmtlib to 11.0.2, like fbcode_builder does, and skip building its test suite to not waste time.
• Use Ninja to generate and build CMake-based dependencies.
• Use googletest, gmock and zstd as packaged by Ubuntu rather than building their older versions from source.
• Introduce and use a new define MCROUTER_OSS_BUILD to mark OSS-specific conditional compilation blocks. This could probably replace the existing LIBMC_FBTRACE_DISABLE and DISABLE_COMPRESSION defines too, as long as those aren't used outside of the OSS build.
• Fix OSS build failures that have gone undetected due to CI being broken:
  • Add a shim for the SR-specific method HostInfoLocation::hostUniqueKey (used since 85facb9).
  • Use folly's FB_LOG_EVERY_MS glog wrapper over a Meta-specific include (used since 6c2142a).
  • Disable client identity propagation in the OSS build since it relies on Meta-specific code (used since 2f32271).

Fixes #453, fixes #444, fixes #447 etc.