feat: initial push with a fully separated and organized user configuration for AstroNvim v3

heirline/attributes.lua

@@ -0,0 +1,5 @@
+-- Customize attributes of highlighting in Heirline components
+return {
+  -- styling choices for each heirline element, check possible attributes with `:h attr-list`
+  git_branch = { bold = true }, -- bold the git branch statusline component
+}