core: add an Arch type (MR 2252)

Move pmb/parse/arch.py over to core and refactor it as an Arch type,
similar to how Chroot was done. Fix all the uses (that I can find) of
arch in the codebase that need adjusting.

The new Arch type is an Enum, making it clear what architectures can be
represented and making it much easier to reason about. Since we support
~5 (kinda) different representations of an Architecture (Alpine, Kernel,
target triple, platform, and QEMU), we now formalise that the Alpine
format is what we represent internally, with methods to convert to any
of the others as-needed.

Signed-off-by: Caleb Connolly <caleb@postmarketos.org>

pmb/helpers/pmaports.py

@@ -8,6 +8,7 @@ See also:
 """
 import glob
 from pmb.core import get_context
+from pmb.core.arch import Arch
 from pmb.core.pkgrepo import pkgrepo_iter_package_dirs
 from pmb.helpers import logging
 from pathlib import Path
@@ -164,6 +165,7 @@ def find(package, must_exist=True, subpackages=True, skip_extra_repos=False):
         # Try to find an APKBUILD with the exact pkgname we are looking for
         path = _find_apkbuilds(skip_extra_repos).get(package)
         if path:
+            logging.verbose(f"{package}: found apkbuild: {path}")
             ret = path.parent
         elif subpackages:
             # No luck, take a guess what APKBUILD could have the package we are
@@ -282,7 +284,7 @@ def get_repo(pkgname, must_exist=True) -> Optional[str]:
     return aport.parent.name
 
 
-def check_arches(arches, arch):
+def check_arches(arches, arch: Arch):
     """Check if building for a certain arch is allowed.
 
     :param arches: list of all supported arches, as it can be found in the
@@ -293,9 +295,9 @@ def check_arches(arches, arch):
 
     :returns: True when building is allowed, False otherwise
     """
-    if "!" + arch in arches:
+    if f"!{arch}" in arches:
         return False
-    for value in [arch, "all", "noarch"]:
+    for value in [str(arch), "all", "noarch"]:
         if value in arches:
             return True
     return False