Fix raw format for other commands, add to docs! (#17730)

* Clarify when -format=raw fails

Signed-off-by: Alexander Scheel <alex.scheel@hashicorp.com>

* Document Vault read's new -format=raw mode

Signed-off-by: Alexander Scheel <alex.scheel@hashicorp.com>

* Add raw format to usage, completion

Signed-off-by: Alexander Scheel <alex.scheel@hashicorp.com>

* Add missing support for raw format field printing

Signed-off-by: Alexander Scheel <alex.scheel@hashicorp.com>

* Prohibit command execution with wrong formatter

This allows us to restrict the raw formatter to only commands that
understand it; otherwise, when running `vault write -format=raw`, we'd
actually hit the Vault server, but hide the output from the user. By
switching this to a flag-parse time check, we avoid running the rest of
the command if a bad formatter was specified.

Signed-off-by: Alexander Scheel <alex.scheel@hashicorp.com>

Signed-off-by: Alexander Scheel <alex.scheel@hashicorp.com>

command/base_helpers.go

@@ -322,3 +322,20 @@ func generateFlagWarnings(args []string) string {
 		return ""
 	}
 }
+
+func generateFlagErrors(f *FlagSets, opts ...ParseOptions) error {
+	if Format(f.ui) == "raw" {
+		canUseRaw := false
+		for _, opt := range opts {
+			if value, ok := opt.(ParseOptionAllowRawFormat); ok {
+				canUseRaw = bool(value)
+			}
+		}
+
+		if !canUseRaw {
+			return fmt.Errorf("This command does not support the -format=raw option.")
+		}
+	}
+
+	return nil
+}