[SECURITY] Notify users about account security changes

- Currently if the password, primary mail, TOTP or security keys are
changed, no notification is made of that and makes compromising an
account a bit easier as it's essentially undetectable until the original
person tries to log in. Although other changes should be made as
well (re-authing before allowing a password change), this should go a
long way of improving the account security in Forgejo.
- Adds a mail notification for password and primary mail changes. For
the primary mail change, a mail notification is sent to the old primary
mail.
- Add a mail notification when TOTP or a security keys is removed, if no
other 2FA method is configured the mail will also contain that 2FA is
no longer needed to log into their account.
- `MakeEmailAddressPrimary` is refactored to the user service package,
as it now involves calling the mailer service.
- Unit tests added.
- Integration tests added.

models/user/email_address_test.go

@@ -43,40 +43,6 @@ func TestIsEmailUsed(t *testing.T) {
 	assert.False(t, isExist)
 }
 
-func TestMakeEmailPrimary(t *testing.T) {
-	assert.NoError(t, unittest.PrepareTestDatabase())
-
-	email := &user_model.EmailAddress{
-		Email: "user567890@example.com",
-	}
-	err := user_model.MakeEmailPrimary(db.DefaultContext, email)
-	assert.Error(t, err)
-	assert.EqualError(t, err, user_model.ErrEmailAddressNotExist{Email: email.Email}.Error())
-
-	email = &user_model.EmailAddress{
-		Email: "user11@example.com",
-	}
-	err = user_model.MakeEmailPrimary(db.DefaultContext, email)
-	assert.Error(t, err)
-	assert.EqualError(t, err, user_model.ErrEmailNotActivated.Error())
-
-	email = &user_model.EmailAddress{
-		Email: "user9999999@example.com",
-	}
-	err = user_model.MakeEmailPrimary(db.DefaultContext, email)
-	assert.Error(t, err)
-	assert.True(t, user_model.IsErrUserNotExist(err))
-
-	email = &user_model.EmailAddress{
-		Email: "user101@example.com",
-	}
-	err = user_model.MakeEmailPrimary(db.DefaultContext, email)
-	assert.NoError(t, err)
-
-	user, _ := user_model.GetUserByID(db.DefaultContext, int64(10))
-	assert.Equal(t, "user101@example.com", user.Email)
-}
-
 func TestActivate(t *testing.T) {
 	assert.NoError(t, unittest.PrepareTestDatabase())