Initial code change of unittest cases for file cmdlets.
BUG:2137142 - [NodeJS] Failed to upload File if path is omitted.

This bug is because of a regression introduced by path normalize. Null check is missed.
BUG:2037247 - [NodeJS] GetShareByPrefixUsingWildCardTest failed because * is taken as valid character by NodeJS SDK

Both NodeJS SDK and .Net xSCL didn't validate share prefix for their purpose. Their design seems to just return nothing if a prefix is not valid (and could never be a prefix of any possible share name).

For our cmdlet, I believe it would be better to fail earlier. So I did this change to validate the prefix on our own and follows the same behavior of powershell cmdlets.
Merge branch 'sprint38'
Record nock result for test cases.
Replace storage account yanhfiletest in nock recording files with xplat.
Merge branch 'sprint38'