settings: add a missing string for the security key fingerprint dialog

Also change a typo in the aria-label attribute referencing the
previously undefined string.

Bug: 974046
Change-Id: I289a68928d0d1edc55d4c48b28d6e8556cc73e6b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1919825
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
Auto-Submit: Martin Kreichgauer <martinkr@google.com>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#715988}

chrome/app/settings_strings.grdp

@@ -5376,6 +5376,9 @@
   <message name="IDS_SETTINGS_SECURITY_KEYS_NO_BIOMETRIC_ENROLLMENT" desc="An error message shown when a user attempts to use the fingerprint sensor on their security key (an authentication hardware device) but the security key is not capable of storing fingerprints, or does not have a fingerprint sensor.">
     Your security key can't store fingerprints
   </message>
+  <message name="IDS_SETTINGS_SECURITY_KEYS_BIO_ENROLLMENT_DELETE" desc="The label for a button that when clicked deletes a fingerprint from a security key (an authentication hardware device) with a built-in fingerprint reader.">
+    Delete this fingerprint
+  </message>
   <message name="IDS_SETTINGS_SECURITY_KEYS_TOUCH_TO_CONTINUE" desc="A label instructing the user to physically touch the activation button on their security key (an authentication hardware device).">
     To continue, insert and touch your security key
   </message>

chrome/browser/resources/settings/privacy_page/security_keys_bio_enroll_dialog.html

@@ -90,7 +90,7 @@
                       [[item.name]]
                     </div>
                     <cr-icon-button class="icon-clear"
-                        aria-label="i18n{securityKeysBioEnrollmentDelete}"
+                        aria-label="$i18n{securityKeysBioEnrollmentDelete}"
                         on-click="deleteEnrollment_"
                         disabled="[[deleteInProgress_]]">
                     </cr-icon-button>

chrome/browser/ui/webui/settings/settings_localized_strings_provider.cc

@@ -3294,6 +3294,8 @@ void AddSecurityKeysStrings(content::WebUIDataSource* html_source) {
   static constexpr LocalizedString kSecurityKeysStrings[] = {
       {"securityKeysBioEnrollmentAddTitle",
        IDS_SETTINGS_SECURITY_KEYS_BIO_ENROLLMENT_ADD_TITLE},
+      {"securityKeysBioEnrollmentDelete",
+       IDS_SETTINGS_SECURITY_KEYS_BIO_ENROLLMENT_DELETE},
       {"securityKeysBioEnrollmentDialogTitle",
        IDS_SETTINGS_SECURITY_KEYS_BIO_ENROLLMENT_DIALOG_TITLE},
       {"securityKeysBioEnrollmentEnrollingCompleteLabel",