Add support for AArch64/ARM64 EFI architecture (#1757)

* Add AArch64/ARM64 EFI boot support (for QEMU and some boards)
* Allow GRUB to load cmdline.txt-like
* Enable qcow2/vmdk disk images

Co-authored-by: Stefan Agner <stefan@agner.ch>

.github/workflows/release.yml

@@ -119,7 +119,7 @@ jobs:
           asset_content_type: application/x-tar
 
       - name: Upload qcow2 image
-        if: ${{ matrix.board.name == 'ova' }}
+        if: ${{ matrix.board.name == 'ova' || matrix.board.name == 'generic-aarch64' }}
         uses: actions/upload-release-asset@v1
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
@@ -152,7 +152,7 @@ jobs:
           asset_content_type: application/zip
 
       - name: Upload vmdk image
-        if: ${{ matrix.board.name == 'ova' }}
+        if: ${{ matrix.board.name == 'ova' || matrix.board.name == 'generic-aarch64' }}
         uses: actions/upload-release-asset@v1
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}