Add an option to show storage class

[igungor]

s5cmd ls show a custom abbreviation of an objects storage class. It's better to show full name of a class, instead of an abbreviation.

I'm thinking of -s to show storage class. For example;

$ s5cmd ls -s s3://bucket/

2020/05/06 09:35:18               STANDARD   13 a.xml
2020/05/06 09:33:57             ONEZONE_IA   23 a.html
2020/05/06 09:34:31            STANDARD_IA   14 a.json
2020/05/06 09:35:44    INTELLIGENT_TIERING   15 a.md