feat(web-stack): add new i18n guidelines + ESLint + update and fixes (#7753)

- Add new i18n guidelines
- Remove nested keys: `"foo": { "bar": "..." }` ➡️ `"foo.bar": "..."`
  This makes code cleaner (and as a side-effect, it now allows to use `foo` + `foo.bar` keys)
- Lite/6 shared translations are no longer prefixed with `core.`
- Duplicated keys across translation files are no longer accepted.
  This will prevent accidental overwrite of missing common translations
- `fr.json` and `en.json` now required to contains the same keys
- Raw text is no longer accepted in template to prevent forgetting a translation
  Raw text is still accepted in dev-related files (stories, dev pages...)
- Remove useless `alt` on `img`
- Display of percentage now uses `$n(value, 'percent')`
- Removed legacy `lite/src/i18n.ts`
- Add missing translations
- Added visual indicator for missing translations while in dev env: `🌎❗⟨i-am-missing⟩`

.eslintrc.js

@@ -177,6 +177,59 @@ module.exports = {
         'vue/valid-define-options': 'error',
       },
     },
+    // Specific rules for XO i18n-related files
+    {
+      files: [
+        '@xen-orchestra/lite/**/*.{vue,ts,json}',
+        '@xen-orchestra/web/**/*.{vue,ts,json}',
+        '@xen-orchestra/web-core/**/*.{vue,ts,json}',
+      ],
+      extends: ['plugin:@intlify/vue-i18n/base'],
+      settings: {
+        'vue-i18n': {
+          localeDir: [
+            '@xen-orchestra/lite/src/locales/*.json',
+            '@xen-orchestra/web/src/locales/*.json',
+            '@xen-orchestra/web-core/lib/locales/*.json',
+          ],
+          messageSyntaxVersion: '^9.9.0',
+        },
+      },
+      rules: {
+        strict: 'off',
+        'no-irregular-whitespace': 'off',
+        '@intlify/vue-i18n/no-deprecated-i18n-component': 'error',
+        '@intlify/vue-i18n/no-deprecated-i18n-place-attr': 'error',
+        '@intlify/vue-i18n/no-deprecated-i18n-places-prop': 'error',
+        '@intlify/vue-i18n/no-deprecated-modulo-syntax': 'error',
+        '@intlify/vue-i18n/no-deprecated-tc': 'error',
+        '@intlify/vue-i18n/no-html-messages': 'error',
+        '@intlify/vue-i18n/no-i18n-t-path-prop': 'error',
+        '@intlify/vue-i18n/no-missing-keys': 'error',
+        '@intlify/vue-i18n/no-raw-text': [
+          'error',
+          {
+            ignoreText: ['Xen Orchestra Lite', 'Xen Orchestra', 'XO Lite', 'XCP-ng', 'XO 5', '404', '⚠️'],
+          },
+        ],
+        '@intlify/vue-i18n/no-v-html': 'error',
+        '@intlify/vue-i18n/valid-message-syntax': 'error',
+        '@intlify/vue-i18n/no-duplicate-keys-in-locale': 'error',
+        '@intlify/vue-i18n/no-missing-keys-in-other-locales': ['error', { ignoreLocales: ['de'] }],
+      },
+    },
+    // Specific rules for XO dev-related files
+    {
+      files: [
+        '@xen-orchestra/lite/src/stories/**/*',
+        '@xen-orchestra/lite/src/components/component-story/**/*',
+        '@xen-orchestra/web/src/pages/dev/**/*',
+        '@xen-orchestra/lite/src/views/story/**/*',
+      ],
+      rules: {
+        '@intlify/vue-i18n/no-raw-text': 'off',
+      },
+    },
     {
       files: ['@xen-orchestra/{web-core,lite,web}/src/pages/**/*.vue'],
       parserOptions: {