[build]: add branch and release name in sonic_version.yml

the branch refers the branch name that the commit is in,
for example master, 202012, 201911, ...
In case there is no branch, the name will be HEAD.

release is encoded in /etc/sonic/sonic_release file.
the file is only available for a release branch.
It is not available in master branch.

Signed-off-by: Guohan Lu <lguohan@gmail.com>

build_debian.sh

@@ -471,12 +471,17 @@ fi
 
 ## Version file
 sudo mkdir -p $FILESYSTEM_ROOT/etc/sonic
+if [ -f files/image_config/sonic_release ]; then
+    sudo cp files/image_config/sonic_release $FILESYSTEM_ROOT/etc/sonic/
+fi
 sudo tee $FILESYSTEM_ROOT/etc/sonic/sonic_version.yml > /dev/null <<EOF
 build_version: '${SONIC_IMAGE_VERSION}'
 debian_version: '$(cat $FILESYSTEM_ROOT/etc/debian_version)'
 kernel_version: '$kversion'
 asic_type: $sonic_asic_platform
 commit_id: '$(git rev-parse --short HEAD)'
+branch: '$(git rev-parse --abbrev-ref HEAD)'
+release: '$(if [ -f $FILESYSTEM_ROOT/etc/sonic/sonic_release ]; then cat $FILESYSTEM_ROOT/etc/sonic/sonic_release; else echo none; fi)'
 build_date: $(date -u)
 build_number: ${BUILD_NUMBER:-0}
 built_by: $USER@$BUILD_HOSTNAME

platform/vs/sonic-version/build_sonic_version.sh

@@ -2,6 +2,7 @@ tee $1 > /dev/null <<EOF
 build_version: '$sonic_version'
 asic_type: $sonic_asic_platform
 commit_id: '$(git rev-parse --short HEAD)'
+branch: '$(git rev-parse --abbrev-ref HEAD)'
 build_date: $(date -u)
 build_number: ${BUILD_NUMBER:-0}
 built_by: $USER@$BUILD_HOSTNAME