fix(postgresql): provision meson, ninja and winflexbison on windows

- the meson build assumed meson/ninja/win_flex/win_bison/perl on PATH,
  which only held on machines that had them installed
- add meson, ninja and winflexbison tool packages and declare them via
  tools@windows on postgresql, together with the existing strawberry-perl
- meson no longer ships a Windows MSI, so the wheel is installed offline
  into a venv: postgres re-invokes meson through find_program, which
  needs the real meson.exe launcher pip generates

config/pkg/tool/ninja.yml

@@ -0,0 +1,9 @@
+ninja:
+  type: tool
+  artifact:
+    binary:
+      windows-x86_64: { type: url, url: 'https://github.com/ninja-build/ninja/releases/download/v1.13.2/ninja-win.zip', extract: { ninja.exe: '{pkg_root_path}/bin/ninja.exe' } }
+  tool:
+    provides:
+      - ninja.exe
+    binary-subdir: bin