Save detection inference logs to file

[AlexPasqua]

I added the possibility to save the detection logs to file.

The code was almost all there already, just some arguments weren't passed the right way in order to save the detection logs to file.

In case, we could also implement this feature for the other scripts in tools/infer/.

[paddle-bot[bot]]

Thanks for your contribution!

[CLAassistant]

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