util/chroot: add run() method to context class

Rename the ChrootProcDevSys class to just Chroot and add a run() method.
Calls now can be made using:

  with Chroot(root) as chroot:
      chroot.run(command)

stages/org.osbuild.dracut

@@ -1,9 +1,8 @@
 #!/usr/bin/python3
-import subprocess
 import sys
 
 import osbuild.api
-from osbuild.util.chroot import ChrootProcDevSys
+from osbuild.util.chroot import Chroot
 
 
 def yesno(name: str, value: bool) -> str:
@@ -83,12 +82,8 @@ def main(tree, options):
         if initoverlayfs:
             initfs_bin = "/usr/bin/initoverlayfs-install"
 
-        with ChrootProcDevSys(tree):
-            subprocess.run(["/usr/sbin/chroot", tree, initfs_bin,
-                            "--no-hostonly",
-                            "--kver", kver]
-                           + opts,
-                           check=True)
+        with Chroot(tree) as chroot:
+            chroot.run([initfs_bin, "--no-hostonly", "--kver", kver] + opts, check=True)
 
     return 0
 

stages/org.osbuild.update-crypto-policies

@@ -1,23 +1,20 @@
 #!/usr/bin/python3
-import subprocess
 import sys
 
 from osbuild import api
-from osbuild.util.chroot import ChrootProcDevSys
+from osbuild.util.chroot import Chroot
 
 
 def main(tree, options):
     policy = options["policy"]
 
-    with ChrootProcDevSys(tree):
+    with Chroot(tree) as chroot:
         # update-crypto-polciies uses /proc/self/mountinfo to find and verify that fips paths have been mounted to their
         # expected locations by searching for the following path suffixes:
         #   /crypto-policies/default-fips-config
         #   /crypto-policies/back-ends/FIPS
-        cmd = ["/usr/sbin/chroot", tree,
-               "/usr/bin/update-crypto-policies", "--set", policy]
-
-        subprocess.run(cmd, check=True)
+        cmd = ["/usr/bin/update-crypto-policies", "--set", policy]
+        chroot.run(cmd, check=True)
 
     return 0