Status code of not allowed method can be more accurate for Registry REST API

[GeekArthur]

/kind bug

Which area this bug is related to?

/area registry

What versions of software are you using?

Operating System: MAC OS 11.4

Go Pkg Version: go version go1.16.4 darwin/amd64

Bug Summary

Describe the bug:

For registry REST API, currently the status code for not allowed method is 404, we should use 405 instead as it's more accurate

To Reproduce:

Try endpoint https://registry.devfile.io/index with POST method then check the status code

Expected behavior

The status code should be 405 (Method Not Allowed)

Any logs, error output, screenshots etc? Provide the devfile that sees this bug, if applicable.

Additional context

Any workaround?

Suggestion on how to fix the bug