Modernize(Emacs27+) define-minor-mode and fix obsolete incf usage

[zjttyl]

Modernize define-minor-mode and fix obsolete incf usage

• Update define-minor-mode for highlight-symbol-mode and
  highlight-symbol-nav-mode to use keyword arguments (:init-value,
  :lighter, :keymap) instead of deprecated positional arguments.
  Eliminates the "Use keywords rather than deprecated positional
  arguments to ‘define-minor-mode’" warning in Emacs 27+.
• Replace obsolete incf with cl-incf in highlight-symbol-next-color,
  adding (require 'cl-lib) to resolve the "incf is an obsolete alias"
  warning in Emacs 27+. Ensures compatibility with modern Emacs versions.

Fixes issues observed when loading highlight-symbol.el in Emacs 27+.