[FEATURE] Add missing `get` and `update` subcommands for `build` and `buildrun`

[mohit-bhandari45]

Is there an existing feature request for this?

• I have searched the existing feature requests

Is your feature request related to a problem or use-case? Please describe.

Currently, the shp CLI does not support get and update subcommands for build and buildrun resources. Users looking to inspect detailed specifications or update existing Build resources are forced to switch to kubectl get / kubectl edit commands.

In pkg/shp/cmd/build/build.go and pkg/shp/cmd/buildrun/buildrun.go, these missing commands are explicitly noted as technical debt:
// TODO: add support for update and get commands

Describe the solution that you would like.

Implement get and update subcommands for resource managers:

1. shp build get <name> & shp buildrun get <name> to retrieve detailed object specifications and status (supporting table, YAML, or JSON output).
2. shp build update <name> to update an existing Build resource spec via CLI flags or manifest files.

Describe alternatives you have considered.

Using kubectl get build <name> or kubectl edit build <name>, but having native shp subcommands provides a seamless CLI experience consistent with other shp commands like create, list, run, and delete.

Anything else?

No response