fixup! Tor Browser localization migration scripts.

Bug 42203: Migrate about dialog strings to Fluent.

We do not migrate the trademark description since the en-US string
changed.

tools/torbrowser/l10n/migrations/bug-42203-about-dialog.py

+import fluent.syntax.ast as FTL
+from fluent.migrate.helpers import TERM_REFERENCE, transforms_from
+from fluent.migrate.transforms import CONCAT, COPY, REPLACE
+
+
+def migrate(ctx):
+    legacy_path = "aboutDialog.dtd"
+    ctx.add_transforms(
+        "tor-browser.ftl",
+        "tor-browser.ftl",
+        transforms_from(
+            """
+about-dialog-questions-link = { COPY(path, "bottomLinks.questions") }
+about-dialog-grow-tor-network-link = { COPY(path, "bottomLinks.grow") }
+about-dialog-browser-license-link = { COPY(path, "bottomLinks.license") }
+""",
+            path=legacy_path,
+        )
+        + [
+            # Concatenate as
+            #  &project.start;
+            #  <label data-l10n-name="project-link">&project.tpoLink;</a>
+            #  &project.end;
+            #
+            # And replace any occurrence of "&brandShortName;" and
+            # "&vendorShortName;" with "-brand-short-name" and
+            # "-vendor-short-name", wherever they may appear.
+            FTL.Message(
+                id=FTL.Identifier("about-dialog-tor-project"),
+                value=CONCAT(
+                    REPLACE(
+                        legacy_path,
+                        "project.start",
+                        {
+                            "&brandShortName;": TERM_REFERENCE("brand-short-name"),
+                            "&vendorShortName;": TERM_REFERENCE("vendor-short-name"),
+                        },
+                    ),
+                    FTL.TextElement('<label data-l10n-name="project-link">'),
+                    REPLACE(
+                        legacy_path,
+                        "project.tpoLink",
+                        {
+                            "&brandShortName;": TERM_REFERENCE("brand-short-name"),
+                            "&vendorShortName;": TERM_REFERENCE("vendor-short-name"),
+                        },
+                    ),
+                    FTL.TextElement("</label>"),
+                    REPLACE(
+                        legacy_path,
+                        "project.end",
+                        {
+                            "&brandShortName;": TERM_REFERENCE("brand-short-name"),
+                            "&vendorShortName;": TERM_REFERENCE("vendor-short-name"),
+                        },
+                    ),
+                ),
+            ),
+            # Concatenate with two link labels.
+            FTL.Message(
+                id=FTL.Identifier("about-dialog-help-out"),
+                value=CONCAT(
+                    COPY(legacy_path, "help.start"),
+                    FTL.TextElement('<label data-l10n-name="donate-link">'),
+                    COPY(legacy_path, "help.donateLink"),
+                    FTL.TextElement("</label>"),
+                    COPY(legacy_path, "help.or"),
+                    FTL.TextElement('<label data-l10n-name="community-link">'),
+                    COPY(legacy_path, "help.getInvolvedLink"),
+                    FTL.TextElement("</label>"),
+                    COPY(legacy_path, "help.end"),
+                ),
+            ),
+        ],
+    )