Do not save OAS example response if it is over the limit.
SpecGen.MaxExampleLen is measured in bytes.
Limit=0 means "don't record any examples", while limit=-1 means "record all".

Limit is configured via the config file / --set: --set oas.max-example-len=100.
The default is 10KB.

This PR breaks the previous config. Moved oas bool (enable/disable OAS) to oas.enable.
Users who wish to disable OAS (or to explicitly enable it) should now to so with --set oas.enable=false instead of --set oas=false.
Co-authored-by: Nimrod Gilboa Markevich <nimrod@up9.com>
Co-authored-by: Nimrod Gilboa Markevich <59927337+nimrod-up9@users.noreply.github.com>