Add gist/pastry upload to lintrunner rage

[oulgen]

It is convenient to send the result of lintrunner rage a gist. Lets support it natively.

(py311) ~/d/lintrunner ❯❯❯ ./target/debug/lintrunner rage --pastry                                                 main ✱
Warning: Could not find a lintrunner config at: '.lintrunner.private.toml'. Continuing without using configuration file.
✔ Select a past invocation to report · ✕ 2024-04-09T11:03:24.068-07:00: ./target/debug/lintrunner rage --pastry
P1209564520: https://www.internalfb.com/intern/paste/P1209564520/
(py311) ~/d/lintrunner ❯❯❯ ./target/debug/lintrunner rage --gist                                                   main ✱
Warning: Could not find a lintrunner config at: '.lintrunner.private.toml'. Continuing without using configuration file.
✔ Select a past invocation to report · ✓ 2024-04-09T11:09:17.670-07:00: ./target/debug/lintrunner rage --pastry
- Creating gist...
✓ Created secret gist
https://gist.github.com/oulgen/d572796b4e6c7f4c0ba7b373da1b6d0d