feat: Android improvements needed for building NumPy and related packages (#2695)

* Use auditwheel on Android

* Add auditwheel command to defaults

* pkgconfig fixes

* Pre-import ctypes before monkey-patching in _cross_venv

* Set PKG_CONFIG and PKG_CONFIG_RELOCATE_PATHS variables

* Initial attempt at using mzakharo/android-gfortran

* Switch to using termux/ndk-toolchain-clang-with-flang

* Move PKG_CONFIG variables from build_env to android_env

* Simplify flang installation

* Add cross build files for NumPy

* Add ldpaths entry for libomp

* Add `--rm` to docker command line

* Make Rust and Fortran shims consistent

* Update documentation

* Default to API level 24 on all Python versions

* Clarify comments

* Cleanups

* Fix tests:
* Set up Android env after installing pkgconf
* Add tests for successfully using an older API level
* Previous commit's auditwheel failure is fixed in the auditwheel PR

* Update how-it-works diagram

* Add tests for repair errors

* Add more repair tests

* Add test for Meson and Fortran

* Add test for cross build files

* Improve test_api_level error message

* Add xbuild-files option

* use pypa/auditwheel@main

* Remove dependencies which are no longer needed

* Fix README

* Update to auditwheel 6.7.0

* Fix compatibility with pkgconf 2.5.1.post2

* Documentation clarifications

Co-authored-by: Joe Rickerby <joerick@mac.com>

* Fortran shim improvements

* Add Jinja variables to new_meson_project

* Update run_example_ci_configs for changed new_meson_project signature

* Add missing dependency to run_example_ci_configs

---------

Co-authored-by: mayeut <mayeut@users.noreply.github.com>
Co-authored-by: Joe Rickerby <joerick@mac.com>

docs/diagram.html

@@ -179,14 +179,14 @@
           },
         },
         {
-          label: 'Repair wheel',
+          label: 'Repair using auditwheel',
           href: 'options/#repair-wheel-command',
           platforms: ['android'],
           style: 'block',
           tooltip: {
             title: 'CIBW_REPAIR_WHEEL_COMMAND',
             tag: 'Customisable step',
-            description: 'By default, bundles libc++ into the wheel if any shared library links against it, using patchelf. Can be overridden with a custom repair command.'
+            description: 'Bundle shared libraries by running auditwheel on each built wheel.'
           },
         },
         {