Support preview flag when apply walrus file

[aiwantaozi]

Support adding a preview flag when applying walrus file, and support preview output, waiting for preview output

[alexcodelf]

Should we support import walrus file with preview in UI?

[Finenyaco]

Environment

• Walrus version: main 96792e2
• UI version: dev-040e825

Test Result: pass

 ~ w apply -f preview.yaml --preview --wait
resource default/local/nginx2 preview generating
resource default/local/nginx2 preview is generated, changes: 3 created, 0 updated, 0 deleted
 NAME              TYPE                       CHANGE TYPE
----------------- -------------------------- -------------
 ephemeral_files   kubernetes_config_map_v1   create
 deployment        kubernetes_deployment_v1   create
 service           kubernetes_service_v1      create

esource default/local/nginx2 preview generating
resource default/local/nginx2 preview is generated, changes: 0 created, 1 updated, 0 deleted
 NAME                                                               TYPE                       CHANGE TYPE
------------------------------------------------------------------ -------------------------- -------------
 default-local/eph-f-run-0-nginx-432e8a41659fd978d2fbae0a291a4423   kubernetes_config_map_v1   no-change
 default-local/nginx2-w9gk7                                         kubernetes_deployment_v1   update
 default-local/nginx2                                               kubernetes_service_v1      no-change

[gitlawr]

There's no way to apply the planned runs at the moment.

[Finenyaco]

Verified in c6bba6b.

Usage:
  walrus preview [flags]

Examples:
  # Generate preview of the configuration in the walrus-file.yaml
  $ walrus preview -f walrus-file.yaml --run-labels key=value

  # Generate preview of yaml files from a directory
  $ walrus preview -f dir/ --run-labels key=value

  # Generate preview of yamls files from a directory recursively
  $ walrus preview -f dir/ --recursive --run-labels key=value

  # Generate preview of yaml files with a specific project/environment
  $ walrus preview -f dir/ --run-labels key=value -p my-project -e my-environment

  # Apply generated preview with specific labels
  $ walrus preview -f walrus-file.yaml --run-labels key=value --apply

Known issue: #2243