fixup! Tor Browser localization migration scripts.

Bug 42214: Migrate security level strings to Fluent.

tools/torbrowser/l10n/migrations/bug-42214-security-level.py

+from fluent.migrate.helpers import transforms_from
+
+
+def migrate(ctx):
+    ctx.add_transforms(
+        "base-browser.ftl",
+        "base-browser.ftl",
+        transforms_from(
+            """
+security-level-panel-level-standard = { COPY(path, "security_level_standard") }
+security-level-panel-level-safer = { COPY(path, "security_level_safer") }
+security-level-panel-level-safest = { COPY(path, "security_level_safest") }
+security-level-panel-learn-more-link = { COPY(path, "security_level_learn_more") }
+security-level-panel-open-settings-button = { COPY(path, "security_level_open_settings") }
+
+security-level-preferences-heading = { COPY(path, "security_level") }
+security-level-preferences-overview = { COPY(path, "security_level_overview") }
+security-level-preferences-learn-more-link = { COPY(path, "security_level_learn_more") }
+security-level-preferences-level-standard =
+    .label = { COPY(path, "security_level_standard") }
+security-level-preferences-level-safer =
+    .label = { COPY(path, "security_level_safer") }
+security-level-preferences-level-safest =
+    .label = { COPY(path, "security_level_safest") }
+
+security-level-summary-standard = { COPY(path, "security_level_standard_summary") }
+security-level-summary-safer = { COPY(path, "security_level_safer_summary") }
+security-level-summary-safest = { COPY(path, "security_level_safest_summary") }
+
+
+security-level-preferences-bullet-https-only-javascript = { COPY(path, "security_level_js_https_only") }
+security-level-preferences-bullet-limit-font-and-symbols = { COPY(path, "security_level_limit_typography") }
+security-level-preferences-bullet-limit-media = { COPY(path, "security_level_limit_media") }
+security-level-preferences-bullet-disabled-javascript = { COPY(path, "security_level_js_disabled") }
+security-level-preferences-bullet-limit-font-and-symbols-and-images = { COPY(path, "security_level_limit_typography_svg") }
+
+security-level-panel-custom-badge = { COPY(path, "security_level_custom") }
+security-level-preferences-custom-heading = { COPY(path, "security_level_custom_heading") }
+security-level-summary-custom = { COPY(path, "security_level_custom_summary") }
+""",
+            path="securityLevel.properties",
+        ),
+    )