Tag-based cache invalidation for prefetch requests

[pascalbaljet]

This PR introduces tag-based cache invalidation for prefetch requests. It enables better control over the prefetch cache without having to flush everything.

There's a new tags prop on the Link components:

<Link href="/users/1" prefetch="hover" :tags="['user', 'profile']">
  View Profile
</Link>

And you can pass it as an option to the prefetch method as well:

router.prefetch(
  '/users',
  { method: 'get', data: { page: 2 } },
  { cacheFor: '1m', tags: ['users'] }
)

The router now has a flushByTags method:

router.flushByTags(['user'])  // Flushes all cache entries tagged with 'user'
router.flushByTags(['user', 'product'])  // Flushes entries tagged with 'user' OR 'product'

When making requests, you can flush tagged cache on a successful request:

router.visit('/users', {
  invalidate: ['user']
})

Or by using the useForm() helper"

form.post('/users', { invalidate: ['users'] })

[pascalbaljet]

Renamed tags to cacheTags and invalidate to invalidateCacheTags. Also added support in the new <Form> component:

<template>
  <Form action="/users" method="post" :invalidate-cache-tags="['user']">
    <input name" type="text" placeholder="Enter name" />
    <button type="submit">Submit</button>
  </Form>
</template>