Enable arm64 builds for Qt 6.8+ on Windows

Squashed commit of the following:

commit 116d38d89528231ec9734a14127c4982cda909d9
Author: Paul Colby <git@colby.id.au>
Date:   Tue Jan 7 21:57:24 2025 +1100

    Restore Linux and macOS builds

commit 904706f
Author: Paul Colby <git@colby.id.au>
Date:   Tue Jan 7 21:47:54 2025 +1100

    Restore all other Windows builds

commit ec336ba
Author: Paul Colby <git@colby.id.au>
Date:   Tue Jan 7 21:36:22 2025 +1100

    Don't exclude arm64 for Qt 6.8+

commit 7753353
Author: Paul Colby <git@colby.id.au>
Date:   Tue Jan 7 21:27:00 2025 +1100

    Exclude some more older Qt's

commit 8f25872
Author: Paul Colby <git@colby.id.au>
Date:   Tue Jan 7 21:23:50 2025 +1100

    Temporarily exclude ealier Qt versions

commit beebec3
Author: Paul Colby <git@colby.id.au>
Date:   Tue Jan 7 21:19:54 2025 +1100

    Try re-enabling Windows arm64 builds with Qt 6.8 and 6.9

.github/workflows/build.yaml

@@ -367,10 +367,6 @@ jobs:
           - { arch: arm64, qt: '5.13.2' }
           - { arch: arm64, qt: '5.14.2' }
           - { arch: arm64, qt: '5.15.2' }
-          # Also exclude arm64 for Qt 6.8+ for now, as Qt 6.8 is moving to native-only (not cross-compiling) arm64 on
-          # Windows (https://www.qt.io/blog/qt-for-windows-on-arm-may21-update) and there are not compatible runners.
-          - { arch: arm64, qt: '6.8.1' } # \todo Qt 6.8.1 might have restored cross-compilation.
-          - { arch: arm64, qt: '6.9.0' } # \todo Qt 6.9.0 might have restored cross-compilation.
           # Exclude MinGW (including LLVM) builds for arm64, since Qt does not provide those binaries yet.
           - { arch: arm64, toolchain: llvm }
           - { arch: arm64, toolchain: mingw }
@@ -469,9 +465,11 @@ jobs:
           - { qt: '6.7.3',   toolchain: msvc,  arch: x86-64, aqtArch: win64_msvc2019_64 }
           # { qt: '6.8.1',   toolchain: llvm,  arch: x86-64, aqtArch: win64_llvm_mingw } \todo See temp exclusion above.
           - { qt: '6.8.1',   toolchain: mingw, arch: x86-64, aqtArch: win64_mingw }
+          - { qt: '6.8.1',   toolchain: msvc,  arch: arm64,  aqtArch: win64_msvc2022_arm64_cross_compiled }
           - { qt: '6.8.1',   toolchain: msvc,  arch: x86-64, aqtArch: win64_msvc2022_64 }
           # { qt: '6.9.0',   toolchain: llvm,  arch: x86-64, aqtArch: win64_llvm_mingw } \todo See temp exclusion above.
           - { qt: '6.9.0',   toolchain: mingw, arch: x86-64, aqtArch: win64_mingw }
+          - { qt: '6.9.0',   toolchain: msvc,  arch: arm64,  aqtArch: win64_msvc2022_arm64_cross_compiled }
           - { qt: '6.9.0',   toolchain: msvc,  arch: x86-64, aqtArch: win64_msvc2022_64 }
           # Map the MSVC architecture.
           - { toolchain: msvc, arch: arm64,  msvcArch: amd64_arm64 }
@@ -512,7 +510,7 @@ jobs:
         uses: jurplel/install-qt-action@v4
         with:
           version: ${{ matrix.qt }}
-          arch: win64_msvc2019_64
+          arch: ${{ startsWith(matrix.aqtArch, 'win64_msvc2019') && 'win64_msvc2019' || 'win64_msvc2022' }}_64
           set-env: false
           # \todo Use aqtinstall HEAD for Qt 6.8.1 and 6.9.0 support, until the fix for #843 is released (presumably in
           # aqtinstall 3.1.22. See https://github.com/miurahr/aqtinstall/issues/843