Prelogin and Login handling for TDS74 FederatedAuth with Security Token

[bowleri]

Fixes #135

[codecov]

Codecov Report

Attention: Patch coverage is 95.37572% with 8 lines in your changes missing coverage. Please review.

Project coverage is 89.19%. Comparing base (585547b) to head (ea3f618).

Files	Patch %	Lines
src/pytds/tds_session.py	95.18%	4 Missing ⚠️
tests/all_test.py	33.33%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #166      +/-   ##
==========================================
+ Coverage   89.10%   89.19%   +0.09%     
==========================================
  Files          44       44              
  Lines        8095     8240     +145     
==========================================
+ Hits         7213     7350     +137     
- Misses        882      890       +8     

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[bowleri]

Appveyor update of ruff from ruff-0.5.1 to ruff-0.5.3 has created failures in tds_types.py

[denisenkom]

Hi @bowleri, thank you for this pull request. I have some questions below.

How can I test this? Maybe you can give me a simple example script that generates access token and nonce, that I could then use against my test Azure account.

It also seems couple validations are missing, can you add those validations?:

• It should fail connection attempt if access_token was provided but server is not supporting TDS 7.4
• It should fail if access_token was provided but contained an empty string

I noticed that you convert access_token into ASCII byte string, this assumes that access_token contains only ASCII characters. Is this assumption safe?