Add intellisense support for new data-enhance, data-enhance-nav, and data-permanent Blazor attributes in .NET 8

[danroth27]

In .NET 8 RC2 we introduced some new attributes that Blazor users can use to control enhanced navigation and form handling:

• data-enhance-nav: Used to turn off enhanced navigation for a specific link or DOM subtree

  <a href="my-non-blazor-page" data-enhance-nav="false">My Non-Blazor Page</a>

• data-enhance: Used to opt in to enhanced form handling for a form element:

  <form method="post" @onsubmit="() => submitted = true" @formname="name" data-enhance>
      <AntiforgeryToken />
      <InputText @bind-Value="Name" />
      <button>Submit</button>
  </form>
  
  @if (submitted)
  {
      <p>Hello @Name!</p>
  }
  
  @code{
      bool submitted;
  
      [SupplyParameterFromForm]
      public string Name { get; set; } = "";
  }

• data-permanent: Used to signal that an element add or updated dynamically should be preserved when handling an enhanced navigation of form request:

  <div data-permanent>
      This div gets updated dynamically by a script when the page loads!
  </div>

We should update the Razor tooling to provide appropriate completions and diagnostic for these attributes.

Related PRs:

• Make enhanced nav much more conservative, and better handle redirections aspnetcore#50551
• [Blazor] APIs to preserve content between enhanced navigations aspnetcore#50437