[IMP] web: remove _lt from env

Having _lt in the env doesn't make much sense, as it is useless
at run time, and it would incite people to require 'web.env' to
use it (at load time). The env should never be directly imported,
it is automatically propagated from parents to children.

To sum up, in Owl components:
 - when terms have to be translated at run time (e.g. in a function
   called when the user clicks on a button), the env is available
   and env._t must be used
 - when terms have to be translated at load time (e.g. a JS module
   defining a component with a translatable static property), one
   must require 'web.translation' and use function _lt it exports.

closes odoo/odoo#50656

Signed-off-by: Géry Debongnie (ged) <ged@openerp.com>

addons/web/static/src/js/env.js

@@ -3,11 +3,12 @@ odoo.define("web.env", function (require) {
 
     const { jsonRpc } = require('web.ajax');
     const { device, isDebug } = require("web.config");
-    const { _lt, _t, bus, serviceRegistry } = require("web.core");
+    const { bus, serviceRegistry } = require("web.core");
     const dataManager = require('web.data_manager');
     const { blockUI, unblockUI } = require("web.framework");
     const rpc = require("web.rpc");
     const session = require("web.session");
+    const { _t } = require('web.translation');
     const utils = require("web.utils");
 
     const qweb = new owl.QWeb({ translateFn: _t });
@@ -131,7 +132,6 @@ odoo.define("web.env", function (require) {
     // See https://github.com/odoo/owl/blob/master/doc/reference/environment.md#content-of-an-environment
     // for more information on environments.
     return {
-        _lt,
         _t,
         bus,
         dataManager,

addons/web/static/src/js/fields/basic_fields_owl.js

@@ -3,9 +3,7 @@ odoo.define('web.basic_fields_owl', function (require) {
 
     const AbstractField = require('web.AbstractFieldOwl');
     const CustomCheckbox = require('web.CustomCheckbox');
-    const core = require('web.core');
-
-    const _lt = core._lt;
+    const { _lt } = require('web.translation');
 
 
     /**

addons/web/static/tests/helpers/test_env.js

@@ -34,7 +34,6 @@ odoo.define('web.test_env', async function (require) {
         let testEnv = {};
         const defaultEnv = {
             _t: env._t || Object.assign((s => s), { database }),
-            _lt: env._lt || Object.assign((s => s), { database }),
             bus: new Bus(),
             device: Object.assign({ isMobile: false }, env.device),
             isDebug: env.isDebug || (() => false),