Upgrade grpc-gateway dependency (#3257)

* proto: correct classification of authz token

The target authorization token had the invalid classification
"private". Fortunately, classification is a fail-closed system,
so this won't have exposed users authorization tokens, but
we should still use the correct classification. Use "secret".

* scripts: add Go script to remove gotags comments

The new version of grpc-gateway includes our gotags
comments in the generate swagger documentation. This
script removes all mentions of these.

* Upgrade grpc-gateway dependency

Mainly we need this to fix generation of our docs side API docs,
but it also includes a nice fix for the new Download RPC, i.e. it
now contains the correct response schema (a binary stream).

scripts/remove-gotags-comments/main.go

@@ -0,0 +1,52 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package main
+
+import (
+	"bytes"
+	"errors"
+	"flag"
+	"fmt"
+	"log"
+	"os"
+
+	"github.com/hashicorp/boundary/internal/observability/event"
+)
+
+var swaggerPath = flag.String("path", "", "The path to the swagger file to parse. Will also be written to")
+
+func main() {
+	flag.Parse()
+
+	if err := run(*swaggerPath); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func run(swaggerPath string) error {
+	if swaggerPath == "" {
+		return errors.New("swagger file path is required")
+	}
+	swaggerBytes, err := os.ReadFile(swaggerPath)
+	if err != nil {
+		return fmt.Errorf("failed to read swagger file: %w", err)
+	}
+	for _, classification := range []event.DataClassification{event.PublicClassification, event.SensitiveClassification, event.SecretClassification} {
+		// Gotag comments appear both with and without the wrapping "`"
+		for _, wrapper := range []string{"", "`"} {
+			// The two cases we're covering are:
+			//   - When gotags appears on its own.
+			//   - When gotags appears at the end of another comment (preceded by \n\n).
+			for _, prefix := range []string{"\\n\\n", ""} {
+				swaggerBytes = bytes.ReplaceAll(swaggerBytes, []byte(fmt.Sprintf("%s@gotags: %sclass:\\\"%s\\\"%s", prefix, wrapper, classification, wrapper)), nil)
+			}
+		}
+	}
+	// Some fields have a comment explaining that their classification is manually managed
+	swaggerBytes = bytes.ReplaceAll(swaggerBytes, []byte("\\n\\nclassified as public via taggable implementation"), nil)
+	if err := os.WriteFile(swaggerPath, swaggerBytes, 0o644); err != nil {
+		return fmt.Errorf("failed to write new swagger file: %w", err)
+	}
+	return nil
+}