Upgrade web to Play 3.0.x

[k2-99]

Note this builds off of this 2.8.x pull request.

Why

Play 2.8.x is EOL

Scope

airline-web

Major Changes

Official Migration Guide

Akka

Akka changed their license. See here for Play's commentary on it. A fork of Akka, called 'Pekko' was created. This request migrates off of Akka onto Pekko.

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Testing

Got airline-web running locally. Did basic testing on airline-web (Create new user/airline, select base, setup some routes). Let me know if you have an SOP for testing and I can do that in the future as well.

[patsonluk]

👋🏼 Many thanks for looking at this! We certainly should update to Play 3!

I have several asks: 🙏🏼

1. Please try not to modify whitespace/indentation at this point, I understand we can do w=1 to view non whitespace changes in Github, however, it will change the line history which makes it hard to trace changes. Currently , we don't have a space coding standard (or tools to enforce it yet), so we might keep flipping back and forth which is not ideal. Im all for standardizing spacing and then format all the code in one go with an agreed spacing policy (or tidy tool that autocheck/fix on commit). But we will need a sepraate PR for that. 😓 For this PR (and other PRs), please stick with existing spacing without modifying them

2. Also for coding standard/convention (whether to use () or not etc), please also do not modify the existing ones (unless it's necessary in PLay 3? Sorry I have not really looked at what Play 3 requires) Again, it will be ideal if we have a set of coding standard for Scala and enforce it across project (via some plugin), but for now, please refrain from modifying those unless it's definitely necesary (again i don't know if it's a PLay 3 requirement. Please lemme know if it is!)

Would it be possible to either modify this PR or start a new PR with minimal changes? Sorry I know this sounds like work, and I totally understand you might not want to. If that's the case, I might start a new PR and pick ur changes manually. 😊

[k2-99]

Closing in favor of #623