Manual - By script
In machine A,
code --list-extensions | xargs -L 1 echo code --install-extension
copy and paste the echo output to machine B
sample output
code --install-extension Angular.ng-template
code --install-extension DSKWRK.vscode-generate-getter-setter
code --install-extension EditorConfig.EditorConfig
code --install-extension HookyQR.beautify