Allow disabling authentication related user features (#31535)

We have some instances that only allow using an external authentication
source for authentication. In this case, users changing their email,
password, or linked OpenID connections will not have any effect, and
we'd like to prevent showing that to them to prevent confusion.

Included in this are several changes to support this:
* A new setting to disable user managed authentication credentials
(email, password & OpenID connections)
* A new setting to disable user managed MFA (2FA codes & WebAuthn)
* Fix an issue where some templates had separate logic for determining
if a feature was disabled since it didn't check the globally disabled
features
* Hide more user setting pages in the navbar when their settings aren't
enabled

---------

Co-authored-by: Kyle D <kdumontnu@gmail.com>

routers/web/user/setting/security/2fa.go

@@ -13,6 +13,7 @@ import (
 	"strings"
 
 	"code.gitea.io/gitea/models/auth"
+	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/web"
@@ -25,6 +26,11 @@ import (
 
 // RegenerateScratchTwoFactor regenerates the user's 2FA scratch code.
 func RegenerateScratchTwoFactor(ctx *context.Context) {
+	if user_model.IsFeatureDisabledWithLoginType(ctx.Doer, setting.UserFeatureManageMFA) {
+		ctx.Error(http.StatusNotFound)
+		return
+	}
+
 	ctx.Data["Title"] = ctx.Tr("settings")
 	ctx.Data["PageIsSettingsSecurity"] = true
 
@@ -55,6 +61,11 @@ func RegenerateScratchTwoFactor(ctx *context.Context) {
 
 // DisableTwoFactor deletes the user's 2FA settings.
 func DisableTwoFactor(ctx *context.Context) {
+	if user_model.IsFeatureDisabledWithLoginType(ctx.Doer, setting.UserFeatureManageMFA) {
+		ctx.Error(http.StatusNotFound)
+		return
+	}
+
 	ctx.Data["Title"] = ctx.Tr("settings")
 	ctx.Data["PageIsSettingsSecurity"] = true
 
@@ -142,6 +153,11 @@ func twofaGenerateSecretAndQr(ctx *context.Context) bool {
 
 // EnrollTwoFactor shows the page where the user can enroll into 2FA.
 func EnrollTwoFactor(ctx *context.Context) {
+	if user_model.IsFeatureDisabledWithLoginType(ctx.Doer, setting.UserFeatureManageMFA) {
+		ctx.Error(http.StatusNotFound)
+		return
+	}
+
 	ctx.Data["Title"] = ctx.Tr("settings")
 	ctx.Data["PageIsSettingsSecurity"] = true
 
@@ -167,6 +183,11 @@ func EnrollTwoFactor(ctx *context.Context) {
 
 // EnrollTwoFactorPost handles enrolling the user into 2FA.
 func EnrollTwoFactorPost(ctx *context.Context) {
+	if user_model.IsFeatureDisabledWithLoginType(ctx.Doer, setting.UserFeatureManageMFA) {
+		ctx.Error(http.StatusNotFound)
+		return
+	}
+
 	form := web.GetForm(ctx).(*forms.TwoFactorAuthForm)
 	ctx.Data["Title"] = ctx.Tr("settings")
 	ctx.Data["PageIsSettingsSecurity"] = true