refactor: reimplement the create cmd for k8s and bare-metal

[shawnh2]

related to: #160, #155, #172

it's a big PR, but it does not introduce anything new, just move the code from an old place to a new place.

some minors in this PR:

• it won't delete all the metadata files or dirs after interrupt the foreground bare-metal cluster, like mentioned in No need to remove metadata when exit foreground bare-metal creation #155

this PR blocks:

• delete cmd refactor
• connect cmd refactor

[zyy17]

lgtm