pipedv1: Mask the plugins config in a piped config

[t-kikuc]

What would you like to be added:

Mask some fields in plugins in a piped config.

We need a discussion on how to realize this feature.

Why is this needed:

In pipedv0, some fields in the piped config were masked to hide secret values on the Web UI.

However, in pipedv1, piped core does not know which fields should be masked.

pipecd/pkg/configv1/piped.go

Lines 141 to 156 in 637fc34

	// Mask masks confidential fields.
	func (s *PipedSpec) Mask() {
	if len(s.PipedKeyFile) != 0 {
	s.PipedKeyFile = maskString
	}
	if len(s.PipedKeyData) != 0 {
	s.PipedKeyData = maskString
	}
	s.Git.Mask()
	s.Notifications.Mask()
	if s.SecretManagement != nil {
	s.SecretManagement.Mask()
	}
	// TODO: Mask plugin configs
	}