allow to configure all hash functions used

[sokra]

fix default hash function for HttpUriPlugin to sha512

add xxhash64 hash function

use xxhash64 as future default

What kind of change does this PR introduce?
feature

Did you add tests for your changes?
no

Does this PR introduce a breaking change?
no

What needs to be documented once your changes are merged?

• output.hashFunction now supports "xxhash64" as fast hashing algorithm

[webpack-bot]

For maintainers only:

• This needs to be documented (issue in webpack/webpack.js.org will be filed when merged)
• This needs to be backported to webpack 4 (issue will be created when merged)

[alexander-akait]

Maybe where we pass hashFunction = "md4" as argument better do it using object options, like:

{ hashFunction = "md4" }

We may need more arguments in the future, so some signatures will be very ugly, just idea

[sokra]

Maybe where we pass hashFunction = "md4" as argument better do it using object options, like:

{ hashFunction = "md4" }

We may need more arguments in the future, so some signatures will be very ugly, just idea

Yeah, I also thought about that, but there is also the issue about memory pressure when creating additional objects.

[webpack-bot]

Thank you for your pull request! The most important CI builds succeeded, we’ll review the pull request soon.

[webpack-bot]

I've created an issue to document this in webpack/webpack.js.org.