Fix two developer-facing annoyances (#9133)

* Fix python ~> python3 in .pre-commit-config.yaml

Using plain `python` requires an active virtual environment,
but our pre-commit Python scripts don't have any dependencies.
It's safe to just use any old python3 that's in the PATH.

* Rename `cmake/vcpkg` to `cmake/vcpkg-ports` and update references.

Author: alexreinking

.pre-commit-config.yaml

@@ -116,13 +116,13 @@ repos:
     hooks:
       - id: check-cmake-file-lists
         name: check CMake file lists
-        entry: python tools/check_cmake_file_lists.py
+        entry: python3 tools/check_cmake_file_lists.py
         language: system
         files: ^test/.*CMakeLists\.txt$
 
       - id: check-cmake-style
         name: check CMake style
-        entry: python tools/check_cmake_style.py
+        entry: python3 tools/check_cmake_style.py
         language: system
         files: (^|/)(CMakeLists\.txt|.*\.cmake)$
 

cmake/vcpkg/llvm/portfile.cmake cmake/vcpkg-ports/llvm/portfile.cmakecmake/vcpkg/llvm/portfile.cmake renamed to cmake/vcpkg-ports/llvm/portfile.cmake

@@ -143,8 +143,8 @@ After broader approval, third-party dependencies must be consumed with
 `find_package`. This also lets packagers and distributors substitute a system or
 pre-built copy, rather than forcing every downstream to rebuild dependencies
 from source. We use vcpkg in CI to manage our dependencies. If vcpkg lacks a
-port, you must write a custom port in `cmake/vcpkg` (for the main Halide build)
-or `apps/vcpkg/ports` (for the apps).
+port, you must write a custom port in `cmake/vcpkg-ports` (for the main Halide
+build) or `apps/vcpkg/ports` (for the apps).
 
 ## Prohibited commands list
 

cmake/vcpkg/llvm/vcpkg.json cmake/vcpkg-ports/llvm/vcpkg.jsoncmake/vcpkg/llvm/vcpkg.json renamed to cmake/vcpkg-ports/llvm/vcpkg.json

@@ -1,6 +1,6 @@
 {
   "overlay-ports": [
-    "cmake/vcpkg"
+    "cmake/vcpkg-ports"
   ],
   "overlay-triplets": [
     "cmake/vcpkg-triplets"