More reality-aligned base URL workflow

[CommandMC]

Base URLs are now always fetched from Epic's CDN, even if there is a manifest override set by the user. This resolves two common issues:

• When providing a manifest URL as the override, Legendary always uses that manifest's URL as the base URL, which usually does not go well (users seem to keep manifest archives, e.g. https://github.com/polynite/fn-releases, without actual game files)
• When providing a manifest override as a file path without ever starting an installation without one, no base URLs will be saved at all

The changes, in my opinion, more accurately reflect how users (especially ones trying to download older Fortnite versions) try to use the manifest override option.

The functionality to provide your own base URLs is not completely lost however, as there's still the --base-url parameter. However, I've never actually seen that parameter be used in the wild.

[God-damnit-all]

This is going to cause issues with PSO2 Tweaker, which a lot of people use as a replacement launcher for Phantasy Star Online 2.

It sets the following overrides:

    "base_urls": [
      "https://fastly-download.epicgames.com/Builds/Org/o-72ykcvlbes9fxdcfyzs4f6u3q3xquc/edd7b759e98447aaa1f72b683f2a4df8/default",
      "https://epicgames-download1.akamaized.net/Builds/Org/o-72ykcvlbes9fxdcfyzs4f6u3q3xquc/edd7b759e98447aaa1f72b683f2a4df8/default",
      "https://download.epicgames.com/Builds/Org/o-72ykcvlbes9fxdcfyzs4f6u3q3xquc/edd7b759e98447aaa1f72b683f2a4df8/default",
      "https://cloudflare.epicgamescdn.com/Builds/Org/o-72ykcvlbes9fxdcfyzs4f6u3q3xquc/edd7b759e98447aaa1f72b683f2a4df8/default"
    ],

They could change to use --base-url but I'm not sure if that parameter can even be used multiple times and, if so, in what order it will prioritize the URLs. That would have to be documented. And honestly, is this really important enough to warrant a breaking change?

[Aida-Enna]

This is going to cause issues with PSO2 Tweaker, which a lot of people use as a replacement launcher for Phantasy Star Online 2.

It sets the following overrides:

    "base_urls": [
      "https://fastly-download.epicgames.com/Builds/Org/o-72ykcvlbes9fxdcfyzs4f6u3q3xquc/edd7b759e98447aaa1f72b683f2a4df8/default",
      "https://epicgames-download1.akamaized.net/Builds/Org/o-72ykcvlbes9fxdcfyzs4f6u3q3xquc/edd7b759e98447aaa1f72b683f2a4df8/default",
      "https://download.epicgames.com/Builds/Org/o-72ykcvlbes9fxdcfyzs4f6u3q3xquc/edd7b759e98447aaa1f72b683f2a4df8/default",
      "https://cloudflare.epicgamescdn.com/Builds/Org/o-72ykcvlbes9fxdcfyzs4f6u3q3xquc/edd7b759e98447aaa1f72b683f2a4df8/default"
    ],

They could change to use --base-url but I'm not sure if that parameter can even be used multiple times and, if so, in what order it will prioritize the URLs. That would have to be documented. And honestly, is this really important enough to warrant a breaking change?

We don't override any of the base URL stuff in the PSO2 Tweaker (I don't even know how the epic backend stuff works, we just hand it over to legendary to handle)