Accept and ignore a file's trusted, and give each runtime its own time to answer

The fourth review (hq issue 339): `trusted` is the catalogue's word and the
controller takes it out, but a controller that passes it on, an older one or
one rolled back to, must not cost a node its whole declaration. A file now
accepts it and nothing reads it; any other resource still refuses it. And a
podman that hangs no longer eats docker's ten seconds.

internal/declaration/declaration.go

@@ -198,6 +198,12 @@ type File struct {
 	// by looking rather than by knowing which field won.
 	Sealed string `json:"sealed,omitempty"`
 
+	// Trusted is the catalogue's word on whether the settings this file's content took are trusted (novox/hq
+	// issue 339). It is the controller's to act on, and a controller takes it out before it sends a declaration.
+	// Accepted here, and nothing is done with it, so that a controller that passes it on — an older one, or one
+	// rolled back to — never costs a node its whole declaration. Not part of the file's digest.
+	Trusted *bool `json:"trusted,omitempty"`
+
 	// Secrets are sealed values put into Content where it says `${secret:name}`.
 	//
 	// **The one place a secret and a configuration meet, and it happens on the machine.** A