parse: apkindex: fix provider_priority never actually being an int

provider_priority was actually a string all along! make it an int as type hinting suggests, and add some tests for apkindex parsing.

cc: @Newbyte

pmb/core/crosstool.py

-# Copyright 2024 Caleb Connolly
-# SPDX-License-Identifier: GPL-3.0-or-later
-
-import enum
-from pathlib import Path
-
-from pmb.core.chroot import ChrootType
-from pmb.types import PathString
-
-
-class CrossToolTarget(enum.Enum):
-    BUILDROOT = 0
-    ROOTFS = 1
-
-
-class CrossTool:
-    __target: CrossToolTarget
-    __package: str
-    __paths: list[Path]
-
-    def __init__(self, target: CrossToolTarget, package: str, paths: list[PathString]):
-        self.__target = target
-        self.__package = package
-        self.__paths = list(map(lambda p: Path(p) if isinstance(p, str) else p, paths))
-
-    def __repr__(self) -> str:
-        return f"CrossTool({self.__target}, {self.__package}, {self.__paths})"
-
-    @property
-    def package(self) -> str:
-        return self.__package
-
-    @property
-    def paths(self) -> list[Path]:
-        return self.__paths
-
-    def should_install(self, target: ChrootType) -> bool:
-        if target == ChrootType.BUILDROOT and self.__target == CrossToolTarget.BUILDROOT:
-            return True
-        if (
-            target == ChrootType.ROOTFS
-            or target == ChrootType.INSTALLER
-            and self.__target == CrossToolTarget.ROOTFS
-        ):
-            return True
-
-        return False