[Godot 4] TextSettings would be better than LabelSettings

[Overvault-64]

While being able to add font files directly in theme and theme overrides is (slightly) more comfortable than having to create a DynamicFont.tres, in Godot 4 we totally lost the ability to synchronize font settings through different nodes and node types.

Up to Godot 3.5.1, I used a DynamicFont - let's say "small.tres", set my font file, and use it across all my nodes: labels, rtlabels, buttons, lineedits, textedits basically every type of node with text. Changing the font size in small.tres would reflect across the whole project.

Now you have to MANUALLY change theme_override_font_sizes/font_size for every single node in your project (with high risk of leaving some behind). The only exception being Label nodes thanks to the LabelSettings class. This contributes to what I feel like fragmentation of text management in Godot.

I propose adding a "TextSettings" class usable across all node classes that have text, like the ones I mentioned above, containing the most common text properties, like Font, Font size, Font color, maybe shadow-related things, etc.