Change hashes to SRI format

[AndersonTorres]

Issue description

The various hashes should be unified to the most recent SHA256 SRI format.

Steps to reproduce

A simple RG can find them. I have tried

rg 'sha256 = "(sha256:|)...................................................."' 

and found the files below:

http://ix.io/3Zoq

[elikoga]

wondering: Would this cause a mass-rebuild?

[AndersonTorres]

wondering: Would this cause a mass-rebuild?

Ideally not. Many of those packages are leaves.

The machine-generated can be problematic, however.

[milahu]

The various hashes should be unified to the most recent SHA256 SRI format.

why?

[AndersonTorres]

why?

Because reasons.

[winterqt]

Also see NixOS/rfcs#131.

[sternenseemann]

I'm closing this since the RFC is still under discussion. It is (as of writing this) just a proposal and there hasn't even been a shepherd discussion yet. We should defer any (treewide) actions until we have come to a decision.

I specifically want to avoid a situation as with the version format RFC where facts were created in nixpkgs and it later turned out that the actions taken were not necessarily the way to go.