[lpm-builder] multi-arch support

[onur-ozkan]

Support multiple architectures from single template file (arch-specific fields should be handled in a separate field named with the architecture/repository name).

arch-specific fields are:

• mandatory_dependencies
• suggested_dependencies
• file_checksum_algo
• version

[onur-ozkan]

Example of multi-arch compatible template:

{
    "name": "",
    "description": "",
    "maintainer": "",
    "source_repository": "",
    "homepage": "",
    "kind": "",
    "tags": [],
    "license": "GPL-3.0-or-later",
    "builds": {
        "amd64": {
            "file_checksum_algo": "sha256",
            "version": {
                "readable": "0.0.0",
                "major": 0,
                "minor": 0,
                "patch": 0
            },
            "mandatory_dependencies": {
                "build": [],
                "runtime": []
            },
            "suggested_dependencies": {
                "build": [],
                "runtime": []
            }
        },
        "source": {
            "version": {
                "readable": "0.0.0",
                "major": 0,
                "minor": 0,
                "patch": 0
            },
            "mandatory_dependencies": {
                "build": [], // There can't be build time dependencies for source packages
                "runtime": []
            },
            "suggested_dependencies": {
                "build": [], // There can't be build time dependencies for source packages
                "runtime": []
            }
        }
    }
}