Content range requests past EOF will fail witth the current version of vapor. It is common practice to just return the remaining bytes rather than throw a bad request error. This helps existing imperfect clients, still out there in the wild to continue to function.

This change captures an attempt to read past EOF (eg a range request of 10-200, when there are only 180 bytes in the file), and returns a response of "partial content" and the remaining bytes. It replaces code that returned a "bad request" error.

The existing tests have been updated to reflect this change and test for a response of type "partial content".
In addition two new asserts have been added to a test:

• The response header content range meets expectation
• The response body byte count meets expectation

As well as passing all tests, the code has been tested with a real life test case.

NOTE: The test 'AsyncRouteTests.testGH2716()' does not not pass. However, it does not pass on the vapor/main branch from which this has been forked.