[SYNPY-1483] Update default order for credential provider

[BryanFauble]

Problem:

1. There have been 2 service desk tickets from folks unable to use synapse login -p $AUTH_TOKEN due to having a synapse config that might not have the appropriate data.

Solution:

1. Updating the credential chain to use CLI arguments first

Testing:

1. Verified that setting -p is used if supplied, but not if not supplied:
   

[pep8speaks]

Hello @BryanFauble! Thanks for opening this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file synapseclient/core/credentials/credential_provider.py:

Line 212:89: E501 line too long (116 > 88 characters)
Line 213:89: E501 line too long (120 > 88 characters)

[rxu17]

LGTM!