Blazor: Let browser handle hash change

[davhdavh]

Background and Motivation

As I can see there are 3 cases with hash:
a. Navigate to a hash on a different page. That was addressed in #8393
b. Blazor uses hash for page navigation. That is #6175 .
c. Navigate to a hash on the current page.

This request is to address the latter.

As I can see there are 3 behaviors that a developer might want:

1. Let the browser deal with it.
2. DOM event listener for popstate or hashchange and handle navigation event via javascript.
3. SSR (current)

The current behavior for blazor.web.js is pretty broken IMHO: Blazor makes a full intercept and a full SSR and then uses the feature from #8393 to navigate to the element.

From the point of view of Blazor 1 and 2 are identical in the fact that if Blazor does nothing, that is the default browser behavior.

Proposed API

Add ignoreHashNavigationOnSamePage to SsrStartOptions.

Alternatively, respect <meta name="ignoreHashNavigationOnSamePage" /> (or something similar), so the individual page can handle it through <HeadContent>.

Alternatively, my preferred behavior: make it the default (It makes no sense to do a SSR on same-page hash change).

Risks

There might be someone somewhere that actually reads url hash server-side.

[mssucksalot]

@MackinnonBuck Your fix still prevents hashchange event, if I need custom logic in vanilla js to be aside Blazor then I have a problem.