add experimental WebAssembly support

[sokra]

What kind of change does this PR introduce?
feature

Did you add tests for your changes?
yes

If relevant, link to documentation update:
TODO

Summary
add Module.type
add wasm, json, js/auto and js/esm types
allow to set type by rules
set default type by extension
allow Main/ChunkTemplate to generate multiple assets
add more parsers for different types
parser plugins should now add by module type

Does this PR introduce a breaking change?
yes

Other information

[webpack-bot]

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[rhmoller]

Hi,

I have been experimenting with this branch. It seems to build fine but webpack-dev-server is unable to run it. The .module.wasm gets served as application/octet-stream instead of application/wasm.

First the mime module does not know the .wasm extension and secondly the middleware.js appends "; charset=UTF-8" to all content types which it should not do for wasm.

See https://github.com/rhmoller/webpack-webassembly-tester

[TheLarkInn]

Thanks for this. I'm going to have @shellscape dig into this specifically for WDS/WDM

[shellscape]

Once this is merged we'll have to setup a test in WDS that fails and I can work backwards from there. I don't have any web assembly experience so I'm not sure how to setup that up at the moment.

[TheLarkInn]

@rhmoller, do you have interest in assisting @shellscape with setting this up? It would be very beneficial to have the support for WDS aw soon as possible even if it merges only to the webpack/webpack#next branch.

[rhmoller]

Sure, I would love to help moving this forward.
I guess it will start with an extra test for the .wasm extension around here
https://github.com/webpack/webpack-dev-middleware/blob/master/test/Server.test.js#L57-L62

[rhmoller]

I have a created an issue for the dev-server issue here. I will add details and work on a pull request there.

webpack/webpack-dev-middleware#229