[clang-tidy] Install run-clang-tidy.py as run-clang-tidy

[Flow]

Summary

Installed scripts in PATH usually do not carry a filename extension,
since there is no need to know that this is a Python script. For
example Debian and Ubuntu already install this script as
'run-clang-tidy' [1] and hence build systems like Meson also look for
this name first [2].

This changes was suggested by Sylvestre Ledru [3].

1: https://salsa.debian.org/pkg-llvm-team/llvm-toolchain/-/blob/60aefb14171ab5c3867a0081844b507fc9f6e015/debian/clang-tidy-X.Y.links.in#L2
2: https://github.com/mesonbuild/meson/blob/b6dc4d5e5c6e838de0b52e62d982ba2547eb366d/mesonbuild/scripts/clangtidy.py#L44
3: https://reviews.llvm.org/D90972#2380640

[Flow]

All changes introduced by this are now done in https://reviews.llvm.org/D90972

clang-tools-extra/clang-tidy/tool/CMakeLists.txt

   COMPONENT clang-tidy)
 install(PROGRAMS run-clang-tidy.py
   DESTINATION bin
-  COMPONENT clang-tidy)
+  COMPONENT clang-tidy
+  RENAME run-clang-tidy)