refactor(router-core): split loadMatches into its own file (#4969)

After the "flattening" PR #4961,
we now have a very clear *separate responsibility* the `Router` class is
handling: loading matches.

This PR proposes we split the code that handles "loading matches" into
its own `load-matches.ts` file, with the entry points being
- `loadMatches`
- `loadRouteChunk`

In future PRs, we might consider splitting other responsibilities out of
the 3k LoC `router.ts` file

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

Author: 2 people

packages/router-core/src/index.ts

@@ -39,6 +39,8 @@ export type {
   RequiredToOptions,
 } from './link'
 
+export { componentTypes } from './load-matches'
+
 export type {
   RouteToPath,
   TrailingSlashOptionByRouter,
@@ -197,7 +199,6 @@ export {
   defaultSerializeError,
   getLocationChangeInfo,
   RouterCore,
-  componentTypes,
   lazyFn,
   SearchParamError,
   PathParamError,