Use activeEditor.options.tabSize for indent_width

[docwhat]

Your plugin should use the current editor's tab size (activeEditor.options.tabSize) for indenting (indent_width) instead of always defaulting to "4".

Ideally, the override order should be:

1. Local .lua-format file.
2. Active editor's tab size.
3. Global user's .lua-format.
4. Plugin defaults.