support implicit data type conversion

for the online request mode, there is no implicit conversion from int to double. There is an error "Translate to request row failed in array row 0" if the input is "1" but the data type is double.

Please confirm we do not support any implicit conversion right now? @aceforeverd @vagetablechicken @dl239

Look at the online request mode handling, likely in request processing or type conversion modules. The error 'Translate to request row failed in array row 0' indicates a mismatch when input '1' (int) is provided for a double column. Examine the code path for request translation and type validation. Determine where implicit conversions could be added, considering database type system and ML feature consistency. Testing involves verifying that int inputs are accepted for double columns without error in online mode.

Written by the indexing model from the issue text.