[core] Add searchParams support to navigation items

[jayenashar]

• I've read and followed the contributing guide on how to create great pull requests.
• I've updated the relevant documentation for any new or updated feature.
• I've linked relevant GitHub issue with "Closes Include search params in toolpad navigation #4537".
• I've added a visual demonstration in the form of a screenshot or video.

Summary

This PR adds support for search parameters in Toolpad navigation items, addressing #4537.

Changes

• Added searchParams property to NavigationPageItem: Navigation items can now specify URL search parameters
• Updated Link component: Preserves search params and hash fragments during navigation
• Implemented hierarchical searchParams merging: Child items inherit parent searchParams by default, with ability to override or clear
• Fixed path matching: matchPath now correctly matches on pathname only, ignoring search params for active page detection
• Added documentation: Documented the new feature in the Dashboard Layout navigation section

API Usage

const nav = [
  {
    segment: 'movies',
    searchParams: new URLSearchParams({ foo: 'bar', baz: 'quux' }),
    children: [
      {
        segment: 'lotr',
        searchParams: new URLSearchParams({ foo: 'hello' }),
        // Result: /movies/lotr?foo=hello&baz=quux (overrides foo, inherits baz)
      },
      {
        segment: 'hp',
        // Result: /movies/hp?foo=bar&baz=quux (inherits all)
      },
      {
        segment: 'dune',
        searchParams: new URLSearchParams(),
        // Result: /movies/dune (empty params clear inheritance)
      },
    ],
  },
];

Implementation Details

• Parent searchParams are inherited by children by default
• Child searchParams override specific parent parameters (merge behavior)
• Empty URLSearchParams() clears all inherited parameters
• Navigation matching ignores search params for correct active page detection
• Hash fragments are now preserved during navigation

Testing

• Added comprehensive test suite for navigation path building with searchParams
• Added tests for Link component to verify search params and hash preservation
• All new tests passing ✓

Documentation

Added a new section "Navigation with search parameters" to the Dashboard Layout documentation with usage examples and key behaviors.

Closes #4537

[Janpot]

I strongly advise against opening pull requests in this repository, at the moment the team doesn't have the bandwidth to review them.