Use stable files API URLs for vendor logo fields

CommonThirdParty.logoUrl and TrustCenterReference.logoUrl were
returning expiring S3 presigned URLs, which break if cached or
shared past their TTL.

Replace with stable /api/files/v1/{id} application URLs.
file.Service now generates these via baseurl; a new filesign
package owns presigning for the files/v1 HTTP handler that
does the internal redirect.

Signed-off-by: Ludovic Vielle <ludovic@probo.com>

pkg/server/server.go

@@ -30,7 +30,7 @@ import (
 	"go.probo.inc/probo/pkg/connector/provider"
 	"go.probo.inc/probo/pkg/cookiebanner"
 	"go.probo.inc/probo/pkg/esign"
-	"go.probo.inc/probo/pkg/file"
+	"go.probo.inc/probo/pkg/filesign"
 	"go.probo.inc/probo/pkg/geoloc"
 	"go.probo.inc/probo/pkg/iam"
 	"go.probo.inc/probo/pkg/iam/oauth2server"
@@ -54,7 +54,7 @@ type Config struct {
 	AllowedOrigins    []string
 	ExtraHeaderFields map[string]string
 	Probo             *probo.Service
-	File              *file.Service
+	FileSign          *filesign.Service
 	IAM               *iam.Service
 	Trust             *trust.Service
 	ESign             *esign.Service
@@ -92,7 +92,7 @@ func NewServer(cfg Config) (*Server, error) {
 		BaseURL:           cfg.BaseURL,
 		AllowedOrigins:    cfg.AllowedOrigins,
 		Probo:             cfg.Probo,
-		File:              cfg.File,
+		FileSign: cfg.FileSign,
 		IAM:               cfg.IAM,
 		Trust:             cfg.Trust,
 		ESign:             cfg.ESign,