View > Snippets shows up for me in 4.2 EA2 directly under View > SSH.
You might try Tools > Features... > Clear Cache and restart SQL Developer. If that does not work, try...
1. Deleting system_cache under your system188.8.131.52.356.1154 user settings folder, or even
2. Deleting or renaming the entire system184.108.40.206.356.1154 folder
Then restart SQL Developer and skip migration of user settings.
Clearing cache did the trick. Thx