[clang] [LifetimeSafety] Optimize fact storage with IDs and vector-based lookup (PR #165963)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-darwin` running on `doug-worker-3` while building `clang` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/23/builds/15335

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'Clang :: Headers/stdckdint.c' FAILED ********************
Exit Code: 127

Command Output (stdout):
--
# RUN: at line 2
/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang -cc1 -internal-isystem /Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/lib/clang/22/include -nostdsysteminc -triple=x86_64 -emit-llvm -verify -std=c99 /Volumes/RAMDisk/buildbot-root/x86_64-darwin/llvm-project/clang/test/Headers/stdckdint.c -o - | /Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/FileCheck /Volumes/RAMDisk/buildbot-root/x86_64-darwin/llvm-project/clang/test/Headers/stdckdint.c
# executed command: /Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang -cc1 -internal-isystem /Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/lib/clang/22/include -nostdsysteminc -triple=x86_64 -emit-llvm -verify -std=c99 /Volumes/RAMDisk/buildbot-root/x86_64-darwin/llvm-project/clang/test/Headers/stdckdint.c -o -
# .---command stderr------------
# | Could not create process (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang) due to [Errno 24] Too many open files
# `-----------------------------
# error: command failed with exit status: 127

--

********************


```

</details>

https://github.com/llvm/llvm-project/pull/165963