fix: how cloudflare pages adapter checks for static asset request and give start a chance to handle request if not found

[edivados]

PR Checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• infrastructure changes
• Other... Please describe:

What is the current behavior?

There were actually two bugs:

• The complete url is used to check for file endings causing 404 if the url ends with a query param that looks like a file ending.
  http://localhost?test=bad.png would causes 404.
• If the request for the static asset returns anything other than 200 the cloudflare error page will be shown instead of letting solid-start handle the request.

What is the new behavior?

• Only looking at the pathname for file ending.
• If the request for static asset does not return 200 or 304 solid-start handels the request.

Other information

fixes #963

[ryansolid]

Thanks