Add `.editorconfig` for consistent code formatting

[Matejkob]

Xcode 16 added support for the EditorConfig standard[^1]. This allows a project/repo to specify basic formatting rules so the editor can behave correctly.[^2]

[!NOTE] You may need to quit and relaunch Xcode for it to pick up the .editorconfig file after switching to a branch where it's present.[^3]

The added .editorconfig file contains:

# editorconfig.org
root = true

[*]
indent_style = space
indent_size = 2
trim_trailing_whitespace = true
insert_final_newline = true

• root = true: Specifies that this is the top-most .editorconfig file. The file search will stop here.
• indent_style = space: Uses soft tabs (spaces) for indentation instead of hard tabs.
• indent_size = 2: Sets the indentation to 2 columns.
• trim_trailing_whitespace = true: Removes any whitespace characters preceding newline characters.
• insert_final_newline = true: Ensures the file ends with a newline when saving.

These settings apply to all files in the project ([*]).

This change make much easier the process of switch between projects that use 2-space and 4-space indentation (what is quite common in your community).

[^1]: Xcode 16 Beta 2 Release Notes–Source Editor New Features [^2]: Inspired by: Add an EditorConfig file [^3]: Xcode 16 Beta 2 Release Notes–Source Editor Known Issues