handlers: refactor errors handling

models/error_extra.go

restapi/handlers/account-template-add.go

restapi/handlers/account-template-delete.go

restapi/handlers/account-template-get.go

restapi/handlers/account-template-list.go

restapi/handlers/account-template-update.go

restapi/handlers/account-template-update_test.go

restapi/handlers/auth-forgot-password.go

restapi/handlers/auth-refresh_token.go

restapi/handlers/auth-register.go

restapi/handlers/auth-reset-password.go

restapi/handlers/auth-userinfo.go

restapi/handlers/errors.go

restapi/handlers/render.go

restapi/handlers/renderlogs.go

restapi/handlers/template-varlist.go

restapi/handlers/user-add.go

restapi/handlers/user-apikey-add.go

restapi/handlers/user-apikey-delete.go

restapi/handlers/user-apikey-list.go