Sorry about making a big PR, probably I can start earlier to split this big PR.
things summary:

1. support more data type

- nullable(date)
- nullable(datetime)
- nullable(datetime64)
- nullable(fixed_string())
- map(string, string)
- array(string)
- array(int64)

2. direct insert support (especially when the target proton, we force to write directly) (reason: upsert query like insert select will timeout sometimes)
3. add a very strong restriction, the target table needs to be created if we use incremental mode and write to target proton database. reason: because now we use direct write, which makes the type conversion and then infer pretty hard. we wanna make user user-created table first. (here we do not check if the user created a buggy table)
4. refine the retry, now we use expo time backoff.
5. refien the temp/internal csv. if we set SLING_KEEP_TEMP then save it, otherwise created in the /app or local sling_transfer folder.

We plan to eliminate the timeout issue during partial inserts by directly writing to the target table instead of using a temporary table. However, when we directly write to the target table, handling type conversion and inference may be a bit tricky. I decided that users will need to create the target table themselves.

TODO:

1. performance improved. I use linux perf wanna check bottleneck but find nothing.