Merge prettier plugins for formatters

[suppayami]

Clear and concise description of the problem

Currently for each supported formatters, the rules overrides plugins field from options.prettierOptions. This makes it hard to use any other prettier plugins, such as prettier-plugin-tailwindcss.

Suggested solution

Merge plugins from prettierOptions with final prettier rules, for example:

antfu({
  formatters: {
    astro: true,
    prettierOptions: {
      plugins: ['prettier-plugin-tailwindcss'],
    },
  },
})

Alternative

Alternative would be this PR, but supporting suggested solution would be easier for most users #592

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guide.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[antfu]

Sounds good, PR welcome :)