feat!: dynamic routes plugin overhaul

[brc-dd]

TODO:

• Review handleHotUpdate code across codebase. Migrate to hotUpdate if needed. Avoid running same hook twice.
  • main plugin
  • hmr fix plugin, fixes markdown snippet changes are not updating the content #4567
  • static data plugin
  • dynamic route plugin -- handle hmr for watch files (track below)
  • local search plugin -- hmr not working (track in separate pr along with other performance fixes and stable index, needs discarding docs from index on deletion/update too)
• Do full page reload on changes in path and data loader files, and their (transitive) deps. Avoid server restart if possible. Ensure that page data is updated.
  • data loader
  • path loader
    • (transitive) deps
    • watched files -- track below
    • page data -- track below
• Allow specifying deps for path loaders - fixes When using "Dynamic Routes" to render raw content, how to keep hot reload working. #4569, fixes Watch files in Path Loader #3937
  • basic implementation
  • cache invalidation and hmr
• fixes [Dynamic Routes]: Add transformPageData configure #2637
  • basic implementation
  • cache invalidation and hmr (route data of dynamic routes isn't updated on hmr, it doesn't pass through the core plugin's handleHotUpdate since the files are virtual)
• out of sync maps in createMarkdownToVueRenderFn (c2ab5b0 didn't fix that because pages are later mapped inside that function)
• import.meta.hot now accepts id instead of url. Fix those.
• Don't use stale cache after full server restart. (Ensure it's always cleared/re-created.) (9f54714)
• Export type helper fn for path loader.
• Add e2e tests for hmr.
• Update docs.