feat(pipectl): add application enable command

[Ahmad-Faraj]

What this PR does:

Adds an application enable command to pipectl.

Why we need it:

An application disabled with pipectl can only be enabled back from the web UI. The API already has EnableApplication, only the CLI command was missing.

Which issue(s) this PR fixes:

None

Does this PR introduce a user-facing change?:

• How are users affected by this change: pipectl application enable is available to enable a disabled application.
• Is this breaking change: No
• How to migrate (if breaking change): Nothing

[Copilot]

Pull request overview

Adds pipectl application enable to let users re-enable applications from the CLI (using the existing EnableApplication API), removing the need to use the web UI for this workflow.

Changes:

• Add a new application enable subcommand that calls apiservice.EnableApplication.
• Register the new subcommand under pipectl application.
• Document the new command in the CLI user guide.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
pkg/app/pipectl/cmd/application/enable.go	Adds the new enable subcommand implementation calling EnableApplication.
pkg/app/pipectl/cmd/application/application.go	Registers newEnableCommand under the application command.
docs/content/en/docs-dev/user-guide/command-line-tool.md	Documents usage of pipectl application enable.