gfx: split text style entity components into a distinct module

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

src/gfx/main.zig

@@ -4,6 +4,7 @@ pub const Atlas = @import("atlas/Atlas.zig");
 // ECS modules
 pub const Sprite = @import("Sprite.zig");
 pub const Text = @import("Text.zig");
+pub const TextStyle = @import("TextStyle.zig");
 
 // Fonts
 pub const Font = @import("font/main.zig").Font;