bootstrap: add a infra to handle pre/post moment of execution maion command

bootstrap: add a infra to handle pre/post moment of execution maion command

bootstrap handles APIs by using Command pattern.
global pre/post commands are executed just after and before execution of the command.
and it gets necessary to handles pre/post moment for each command.
so this patch introduces a infrastructure to handle it.

Change-Id: I2e62cb7b9018ffb020f72666276be55605a588a0