a11y: Fix wrong content descriptions in settings dialogs

[NAME-ASHWANIYADAV]

Fixes #2062

What

• options_language_content.xml: the two language lists in the "Preferred Website Languages" dialog had contentDescription="@string/app_name", so TalkBack announced "Wolvic" (or the flavor's app name) when either list gained accessibility focus. They now use two new translatable strings - "List of preferred languages" / "List of available languages" - added to values/strings.xml with translator comments, following the same pattern as a11y: Label language list icons for screen readers #2040.
• options_exceptions.xml:92: the popup-exceptions list's contentDescription was "privacy_options_popups_list_header_v1" - a literal missing its @string/ prefix, so TalkBack read the raw identifier aloud. The header TextView at :84 already uses the same string correctly with the prefix, so this just restores the intended reference.

Why

Both are wrong announcements from bad contentDescription values in settings dialogs - the first labels the lists with an unrelated string, the second exposes an internal identifier. Each fix matches its bug: the language lists needed correct strings; the exceptions list only needed the missing prefix.

Nothing in the codebase reads these values (no getContentDescription or test usages), so the change is announcement-only with no behavioral surface beyond the screen reader.

If reusing the existing visible header strings (language_options_preferred_languages / language_options_available_languages) is preferred over adding two new translatable strings, happy to switch - the dedicated-string variant was chosen to match #2040.

Testing

• Builds: ./gradlew assembleNoapiArm64GeckoGenericDebug
• Existing unit tests pass: ./gradlew testNoapiArm64GeckoGenericDebugUnitTest

[NAME-ASHWANIYADAV]

@svillar PTAL !!

[svillar]

Thanks! Very much appreciated the a11y fixes