[chore/bugfix] Fix double gzip on prometheus endpoint (#2383)

* [chore] Move "/metrics" into separate API module

* use our own gzip middleware for prom

internal/web/metrics.go

@@ -1,33 +0,0 @@
-// GoToSocial
-// Copyright (C) GoToSocial Authors admin@gotosocial.org
-// SPDX-License-Identifier: AGPL-3.0-or-later
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Affero General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU Affero General Public License for more details.
-//
-// You should have received a copy of the GNU Affero General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-package web
-
-import (
-	"github.com/gin-gonic/gin"
-	"github.com/prometheus/client_golang/prometheus/promhttp"
-)
-
-const (
-	metricsPath = "/metrics"
-	metricsUser = "metrics"
-)
-
-func (m *Module) metricsGETHandler(c *gin.Context) {
-	h := promhttp.Handler()
-	h.ServeHTTP(c.Writer, c.Request)
-}