[clang-tools-extra] Rename CODE_OWNERS -> Maintainers (PR #114544)

[Piotr Zegar via cfe-commits]

================
@@ -0,0 +1,72 @@
+=============================
+Clang Tools Extra Maintainers
+=============================
+
+This file is a list of the maintainers
+(https://llvm.org/docs/DeveloperPolicy.html#maintainers) for clang-tools-extra.
+
+
+Active Maintainers
+==================
+The following people are the active maintainers for the project. Please reach
+out to them for code reviews, questions about their area of expertise, or other
+assistance.
+
+Lead Maintainer
+---------------
+| Aaron Ballman
+| aaron at aaronballman.com (email), aaron.ballman (Phabricator), AaronBallman (GitHub), AaronBallman (Discourse), aaronballman (Discord), AaronBallman (IRC)
+
+
+clang-tidy
+----------
+| Congcong Cai
+| congcongcai0907 at 163.com (email), HerrCai0907 (GitHub), HerrCai0907 (Discourse)
+
+| Julian Schmidt
+| git.julian.schmidt at gmail.com (email), 5chmidti (GitHub), 5chmidti (Discourse), 5chmidti (Discord)
+
----------------
PiotrZSL wrote:

```suggestion

| Piotr Zegar
| me at piotrzegar.pl (email), PiotrZSL (GitHub), PiotrZSL (Discourse), PiotrZSL (Discord)

```


https://github.com/llvm/llvm-project/pull/114544