feat: add VueUse core directives built-in preset

[userquin]

From this issue unplugin/unplugin-vue-components#827 and the PR to fix it unplugin/unplugin-vue-components#828

This PR also includes some changes in the readme file:

• add the built-in presets in the features with a link to the presets folder
• include directives in the Vue features
• add Built-in Preset for VueUse Core Directives section

@antfu we can move this to VueUse, for auto-import we need this PR

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.66%. Comparing base (a4a5e0a) to head (71f9208).
Report is 99 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #432      +/-   ##
==========================================
- Coverage   98.73%   97.66%   -1.08%     
==========================================
  Files          14       15       +1     
  Lines        1817     1453     -364     
  Branches      374      475     +101     
==========================================
- Hits         1794     1419     -375     
- Misses         23       34      +11     

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