Hardcoded English content descriptions in fourteen layouts, two of them inaccurate

[NAME-ASHWANIYADAV]

Fourteen android:contentDescription values across the layout tree are hardcoded English literals rather than @string references, so they never reach the translation pipeline and screen readers announce untranslated English in every locale:

Layout	Line	Value
bookmarks.xml	106	"Bookmarks feed"
history.xml	102	"History feed"
downloads.xml	82	"Downloads"
system_notifications.xml	66	"System notifications"
addons_list.xml	34	"Addons List"
addon_options_permissions.xml	37	"Addons List"
options_saved_logins.xml	93	"Logins List"
prompt_select_login.xml	42	"Saved Logins list"
options_custom_search_engines.xml	82	"Search Engines List"
custom_search_engine_item.xml	87	"Delete custom search engine"
navigation_url.xml	171	"SSL icon"
title_bar.xml	55	"SSL icon"
new_tab.xml	86	"Top sites"
new_tab.xml	109	"Experiences"

These are the last hardcoded values in the tree: of the 38 android:contentDescription occurrences across all 157 layout files (including every flavor directory), the rest are already @string references, several of them from #2039 and the recent settings fix.

Two of the fourteen are not only untranslated but say the wrong thing:

• addon_options_permissions.xml:37 labels @+id/permissions_list as "Addons List". That list holds one add-on's requested permissions (AddonOptionsPermissionsView populates it with addon.translatePermissions(...)), not a list of add-ons.
• navigation_url.xml:171 and title_bar.xml:55 label the icon "SSL icon". Both are the same ic_icon_security_state_insecure drawable shown only when viewmodel.isInsecureVisible is true, so the announcement names the widget and its implementation instead of telling the user the connection is not secure.

The custom_search_engine_item.xml:87 one matters most for operability: it labels the trash icon of an actionable row, so a screen-reader user in a non-English locale gets an English label for a destructive control.

Fix: move all fourteen to translatable strings with translator comments, following the convention used by the existing *_content_description strings, and correct the wording of the inaccurate ones.

Related, but left out

title_bar.xml:67 sets android:contentDescription="Page URL" on the @+id/url TextView. A contentDescription on a TextView replaces its text for accessibility services, so this would normally mask the URL — but that TextView binds its text with tools:text="@{viewmodel.titleBarUrl}", a design-time attribute, so it appears not to be populated at runtime at all. (tools:text with a binding expression appears only twice in the repo - here and addon_options_permissions_item.xml:19.) Deciding the right fix needs a look at what that view actually renders, so it is worth treating separately.