Make repo migration cancelable and fix various bugs (#24605)

Replace #12917

Close #24601
Close #12845


![image](https://github.com/go-gitea/gitea/assets/2114189/39378118-064d-40fb-8396-4579ebf33917)


![image](https://github.com/go-gitea/gitea/assets/2114189/faf37418-191c-46a6-90a8-353141e00e2d)


![image](https://github.com/go-gitea/gitea/assets/2114189/fdc8ee4d-125f-4737-9990-89bcdf9eb388)


![image](https://github.com/go-gitea/gitea/assets/2114189/9a3bd2c2-fe20-4011-81f0-990ed869d139)

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Co-authored-by: Yarden Shoham <git@yardenshoham.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Giteabot <teabot@gitea.io>

options/locale/locale_en-US.ini

@@ -1038,7 +1038,7 @@ migrated_from_fake = Migrated From %[1]s
 migrate.migrate = Migrate From %s
 migrate.migrating = Migrating from <b>%s</b> ...
 migrate.migrating_failed = Migrating from <b>%s</b> failed.
-migrate.migrating_failed.error = Error: %s
+migrate.migrating_failed.error = Failed to migrate: %s
 migrate.migrating_failed_no_addr = Migration failed.
 migrate.github.description = Migrate data from github.com or other GitHub instances.
 migrate.git.description = Migrate a repository only from any Git service.
@@ -1055,6 +1055,8 @@ migrate.migrating_labels = Migrating Labels
 migrate.migrating_releases = Migrating Releases
 migrate.migrating_issues = Migrating Issues
 migrate.migrating_pulls = Migrating Pull Requests
+migrate.cancel_migrating_title = Cancel Migration
+migrate.cancel_migrating_confirm = Do you want to cancel this migration?
 
 mirror_from = mirror of
 forked_from = forked from