stages/io.weldr.grub2: drop unused functions and options

Since we no longer use grub2-mkconfig, but write static configuration
we can drop most of the helpers.

The partitin table id was never used in the first place. We use
filesystem UUIDs, not partition UUIDs to name our root/boot partitions.

Signed-off-by: Tom Gundersen <teg@jklm.no>

samples/base-qcow2.json

@@ -1,6 +1,6 @@
 {
   "name": "base-qcow2",
-  "base": "445c09ba71fd656aadcc2c1e84adb12dcc5fd193fcbdc386b63e2fc02e134e98",
+  "base": "d7f6aca0b9cf09833f70983c20ef3ac6e626152ee99901fc07f26cbf85c2bced",
   "assembler":
     {
       "name": "io.weldr.qcow2",

samples/base-with-grub2.json

@@ -6,8 +6,7 @@
       "name": "io.weldr.grub2",
       "systemResourcesFromEtc": ["/etc/grub.d"],
       "options": {
-        "root_fs_uuid": "76a22bf4-f153-4541-b6c7-0332c0dfaeac",
-	"partition_table_id": "0xdeadbeef"
+        "root_fs_uuid": "76a22bf4-f153-4541-b6c7-0332c0dfaeac"
       }
     }
   ]

stages/io.weldr.grub2

@@ -1,50 +1,11 @@
 #!/usr/bin/python3
 
-import contextlib
 import json
-import math
 import os
-import shutil
-import subprocess
 import sys
 import tempfile
 
-def tree_size(tree):
-    size = 0
-    for root, dirs, files in os.walk(tree):
-        for entry in files + dirs:
-            path = os.path.join(root, entry)
-            size += os.stat(path, follow_symlinks=False).st_size
-    return size
-
-@contextlib.contextmanager
-def mount(source, dest, *options):
-    os.makedirs(dest, 0o755, True)
-    subprocess.run(["mount", *options, source, dest], check=True)
-    try:
-        yield
-    finally:
-        subprocess.run(["umount", "-R", dest], check=True)
-
-@contextlib.contextmanager
-def mount_api(dest):
-    with mount("/dev", f"{dest}/dev", "-o", "rbind"), \
-         mount("/proc", f"{dest}/proc", "-o", "rbind"), \
-         mount("/sys", f"{dest}/sys", "-o", "rbind"), \
-         mount("none", f"{dest}/run", "-t", "tmpfs"):
-             yield
-
-@contextlib.contextmanager
-def loop_device(image):
-    r = subprocess.run(["losetup", "--show", "--find", image], stdout=subprocess.PIPE, encoding="utf-8", check=True)
-    loop = r.stdout.strip()
-    try:
-        yield loop
-    finally:
-        subprocess.run(["losetup", "-d", loop], check=True)
-
 def main(tree, options):
-    partition_table_id = options["partition_table_id"]
     root_fs_uuid = options["root_fs_uuid"]
 
     # Create the configuration file that determines how grub.cfg is generated.