Add user secrets (#22191)

Fixes #22183
Replaces #22187

This PR adds secrets for users. I refactored the files for organizations
and repos to use the same logic and templates. I splitted the secrets
from deploy keys again and reverted the fix from #22187.

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

routers/web/user/setting/secrets.go

@@ -0,0 +1,45 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package setting
+
+import (
+	"net/http"
+
+	"code.gitea.io/gitea/modules/base"
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/setting"
+	shared "code.gitea.io/gitea/routers/web/shared/secrets"
+)
+
+const (
+	tplSettingsSecrets base.TplName = "user/settings/secrets"
+)
+
+func Secrets(ctx *context.Context) {
+	ctx.Data["Title"] = ctx.Tr("secrets.secrets")
+	ctx.Data["PageIsSettingsSecrets"] = true
+
+	shared.SetSecretsContext(ctx, ctx.Doer.ID, 0)
+	if ctx.Written() {
+		return
+	}
+
+	ctx.HTML(http.StatusOK, tplSettingsSecrets)
+}
+
+func SecretsPost(ctx *context.Context) {
+	shared.PerformSecretsPost(
+		ctx,
+		ctx.Doer.ID,
+		0,
+		setting.AppSubURL+"/user/settings/secrets",
+	)
+}
+
+func SecretsDelete(ctx *context.Context) {
+	shared.PerformSecretsDelete(
+		ctx,
+		setting.AppSubURL+"/user/settings/secrets",
+	)
+}