refactor(apps-proxy): inline kai-preview CSP helper into bootstrap handler

Author: pepamartinec

internal/pkg/service/appsproxy/proxy/apphandler/authproxy/kaipreview/bootstrap.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"html/template"
 	"net/http"
+	"strings"
 
 	"github.com/keboola/keboola-as-code/internal/pkg/utils/errors"
 )
@@ -43,7 +44,11 @@ func (h *BootstrapHandler) ServeHTTPOrError(w http.ResponseWriter, r *http.Reque
 		return nil
 	}
 
-	WriteFrameAncestorsCSP(w, h.allowedOrigins)
+	if len(h.allowedOrigins) == 0 {
+		w.Header().Set("Content-Security-Policy", "frame-ancestors 'none'")
+	} else {
+		w.Header().Set("Content-Security-Policy", "frame-ancestors "+strings.Join(h.allowedOrigins, " "))
+	}
 	w.Header().Set("Content-Type", "text/html; charset=utf-8")
 	w.Header().Set("Cache-Control", "no-store")