Add more s3 validation.
Add more s3 validation.

Added more validation to s3 config params.
Updated validator to use the new configuration groups (s3_client_config,
s3_object_config).

InMoji/stapler,oschettler/stapler,simudream/stapler,riyan8250/stapler,sonuku/stapler,flaxandteal/stapler,neerajgoyal12/stapler,aozisik/stapler,CodeSleeve/stapler,AndreasHeiberg/stapler