Support MacOS by command `open -a DOSBox`

• use shell command open -a DOSBox --args for Darwin OS
• use webpack to bundle

file list

1. masm-tasm-0.6.0.vsix is the package published in VSCode extension market, including files for windows system.
2. masm-tasm-0.6.0-nowin.vsix is package without binary file for windows like dosbox.exe and player.exe.