Allow editing the editor settings from inside the project manager

[aaronfranke]

Describe the project you are working on:

Godot Engine, specifically I was reminded of this feature when working on this PR.

Describe the problem or limitation you are having in your project:

There is no way to edit the editor settings in the project manager, you have to open a project to edit the editor settings. This is a bit strange since the settings in editor settings aren't tied to a particular project, and some are only relevant for the project manager, ex:

EDIT: This image was based off some changes that didn't end up merged (the checkboxes). This proposal is still relevant though.

Describe the feature / enhancement and how it helps to overcome the problem or limitation:

Adding a button to the project manager to open up the "Editor Settings" menu would solve this.

Describe how your proposal will work, with code, pseudocode, mockups, and/or diagrams:

I tried implementing it here, but it crashes on launch. It seems that the editor settings menu currently depends on having an EditorNode present (an open project), not sure what would be required to properly untangle this spaghetti.

If this enhancement will not be used often, can it be worked around with a few lines of script?:

The workaround is to open a project.

Is there a reason why this should be core and not an add-on in the asset library?:

Any project will work as a workaround, but this is about improving the project manager.

[Zireael07]

Please please.... I just discovered my stupid freezing on load issue goes away with unchecking "restore scripts on load" but to do that, I had to open another project just to be able to access the editor settings.

[JohnVeness]

As another use case example:

As a new user to Godot, my initial view of the Project Manager window had a too small font for my eyes. Seeing no way to fix that in the Project Manager window itself, I eventually found that if I created a new project, I could change the UI scaling in the main editor settings, which also fixed the Project Manager next time I opened it.

Other people might similarly wish to change the initial theme and so on.

At the moment, as far as I can see the only setting that is changeable in the Project Manager itself is a language drop-down in the top-right. Changing that drop-down to a Settings button (or adding a Settings button alongside the language drop-down if preferred), which brought up a subset of settings applicable to the Project Manager, would be a good fix.