Majorly re-organize modules

- Split large modules into smaller parts (e.g. siren-text-manipulation)
- Organize modules into high level groups:
  - completion
  - core
  - editor
  - languages
  - linting
  - misc
  - navigation
  - projects
  - spelling
  - text-editing
  - version-control
  - windows
  - workspaces

modules/version-control/siren-diff-hl.el

@@ -0,0 +1,19 @@
+;;; siren-diff-hl.el --- jimeh's Emacs Siren: diff-hl configuration.
+
+;;; Commentary:
+
+;; Basic configuration for diff-hl.
+
+;;; Code:
+
+(use-package diff-hl
+  :demand
+  :hook ((dired-mode . diff-hl-dired-mode)
+         (magit-post-refresh-hook . diff-hl-magit-post-refresh))
+
+  :config
+  (global-diff-hl-mode +1)
+  (diff-hl-flydiff-mode +1))
+
+(provide 'siren-diff-hl)
+;;; siren-diff-hl.el ends here