[META] Cleanup the "pwa_extras" submodule

Problem/Motivation

There are multiple recent changes on the main module, ONLY concerning the main module, we should check if any of these also apply to the "pwa_extras" submodule, create "pwa_extras" related issues and link them to this very issue.

List of issues to solve:

• [] 📌 [pwa_extras] Rename the "pwa_extras" submodule Active
• [] 💬 iOS ( v12.x and above ) shows white screen instead of Splash Screen Needs work
• [] #3180236: Apple meta tags →

... ?

Steps to reproduce

Proposed resolution

Cleanup the "pwa_extras" submodule.

Remaining tasks

User interface changes

API changes

Data model changes