allow for directory and file extension in hca upload files command

[parthshahva]

Ticket https://app.zenhub.com/workspace/o/humancellatlas/upload-service/issues/36

[codecov-io]

Codecov Report

Merging #174 into master will increase coverage by 0.01%.
The diff coverage is 90%.

@@            Coverage Diff             @@
##           master     #174      +/-   ##
==========================================
+ Coverage    86.9%   86.92%   +0.01%     
==========================================
  Files          34       34              
  Lines        1291     1308      +17     
==========================================
+ Hits         1122     1137      +15     
- Misses        169      171       +2

Impacted Files	Coverage Δ
hca/upload/cli/upload_command.py	86.66% <90%> (+0.95%)	⬆️

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