Server data filling rework and minor tweaks

[furyzen]

I've made some changes, primarily to fix the server data filling issue, caused by the different naming schemes between betacraft's server index and mojang's version's index.

Some notable changes:

• updated gson to 2.10.1
• populate server indexes before starting to modify the manifests, we can avoid looping through the entire index each edit like that
• we fetch the latest server version compatible with the client (note: it include snapshots too)

Some notes:

• gson seems to REALLY hate when we are using parallelized streams (random deserialization exceptions), so i've took the initiative to remove it
• there are some hardcoded fixes to ensure subversions (ex: a1.2.3a and a1.2.3b) are correctly edited
• i am not well familliar with kotlin, so it's probably very poorly implemented

i know this is not really useful for babric which is focused on b1.7.3 but it would be really cool if this could get reviewed and pushed, thanks in advance!