HTTP Boot arch filtering

[5kt]

Summary

At the moment, by using the httpboot plugin one can use a single URL that is going to be used as boot file URL for the clients, irrespective of their architecture so arm64 and x86_64 clients won't be able to boot.
An extra filter for the vendor class identifier should be added and instead of filtering for HTTPClient only, we should add some extra configuration to filter, for example, for HTTPClient:Arch:00016 for x86_64 clients and make it configurable.

Basic example

Motivation

[damyan]

Blocked by #206 for httpboot