Add support for metrics and pprof (#100)

Adds support for toggling support for `pprof` and metrics:

```yaml
gitea:
  pprofEnabled: true

  metrics:
    enabled: true
    serviceMonitor:
      enabled: true
```

Co-authored-by: josef <josef.nilsen@outlook.com>
Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/100
Reviewed-by: luhahn <luhahn@noreply.gitea.io>
Reviewed-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: JosefWN <josefwn@noreply.gitea.io>
Co-committed-by: JosefWN <josefwn@noreply.gitea.io>

values.yaml

@@ -105,6 +105,11 @@ gitea:
     password: r8sA8CPHD9!bt6d
     email: "gitea@local.domain"
 
+  metrics:
+    enabled: false
+    serviceMonitor:
+      enabled: false
+
   ldap:
     enabled: false
     #name: