commands: add a shell command

This command spawns an interactive shell on your host but inside the
user and mount namespaces that pmbootstrap set up. It is mostly useful
for debugging issues with permissions, etc.

Signed-off-by: Casey Connolly <kcxt@postmarketos.org>

pmb/commands/__init__.py

@@ -17,6 +17,7 @@ from .pkgrel_bump import PkgrelBump
 from .pkgver_bump import PkgverBump
 from .pull import Pull
 from .kconfig import KConfigCheck, KConfigEdit, KConfigMigrate
+from .shell import Shell
 
 """New way to model pmbootstrap subcommands that can be invoked without PmbArgs."""
 
@@ -89,6 +90,8 @@ def run_command(args: PmbArgs) -> None:
             command = PkgverBump(args.packages)
         case "pull":
             command = Pull()
+        case "shell":
+            command = Shell()
         case "kconfig":
             match args.action_kconfig:
                 case "check":