Add get subcommand to get the extension on KubeSphere Cloud

[iawia002]

ref #91 (comment) https://github.com/kubesphere/project/issues/1684

Add a new get subcommand:

$ ksbuilder get tower

Name:     tower
ID:       515518094316151974
Status:   draft

SNAPSHOT ID          VERSION   STATUS      UPDATE TIME
515518094316217510   1.0.0     submitted   2024-05-27 09:37:05

$ ksbuilder get kubeblocks

Name:             kubeblocks
ID:               482307830796264605
Status:           ready
Latest version:   0.6.3

SNAPSHOT ID          VERSION   STATUS   UPDATE TIME
482467633778664626   0.6.2     active   2023-10-12 09:25:26
484202399389459627   0.6.3     active   2023-10-24 08:39:26

/cc @stoneshi-yunify

[stoneshi-yunify]

/lgtm