Webonchain cache management

[peterjah]

Context
Today we save zipped websites in MS user cache. the cache key is only based on the website SC address.
It does not have expiration time.
Thus, if the website is updated, or deleted we will continue serve it from the cache.

User flow
When i update my website i want the cache to be invalided for every user so they can see the latest version.

**Proposition **
Add a nonce system in the websiteStorer contract, that can be read and added to the cache key in massa station.
drawback: we will have to make 1 readSC call anytime
To mitigate this, we could add a possibility to add the nonce in the DNS contract, that will allow to have the nonce without extra sc call

QA testing

• Upload a website, browse it (so it should be cached)
• update or delete it
• browse it again and ensure last version is rendered

[loonggamma]

@gregLibert ping on this to define priority of the task

[gregLibert]

@gregLibert ping on this to define priority of the task

Current priority and milestone are fine

[gregLibert]

This topic should be tackled when we rework the web-on-chain. @SlnPons , please feel free to tag this issue for easier reference and refinement in the future, or not 😁.