support upload 'docx' file and output 'html' string in the asterius pandoc online demo

[pasicopan]

Is your feature request related to a problem? Please describe.

related problem: https://github.com/tweag/asterius/issues/89

Describe the solution you'd like

need convert from 'docx' to 'html' , eg. pandoc demo support upload 'docx' file and output 'html' string

Describe alternatives you've considered

show me some code of https://asterius.netlify.app/demo/pandoc/pandoc.html

Additional context why the WASM file of pandoc demo from asterius is so smaller then https://github.com/y-taka-23/wasm-pandoc, 8M VS 65M !!!