Manage attachments cache

Problem/Motivation

There's no cache management at all in the hook_page_attachments() so we might have the wrong user name and email send to JS.
According to Cacheability of render arrays, we should have user:[uid] and config:markerio.settings as cache tags + user as cache contexts.

How to reproduce

On a website instance where there is cache control activated (let say s-maxage=7200 or maxage=7200 which is 10min cache)
Being connected with user uid=1, go on a page where there is no user cache context defined, flush the website cache and reload the page => The JS has now username and mail for user uid=1 which is what we want.
Don't flush the cache, logout and come back to that same page with an anonymous user => JS still has username and mail for user uid=1 which is absolutely not what we want.