support env to turn off imds && add some test cases && fix some bugs

[yndu13]

You need to complete

• unit tests and/or feature tests
• documentation is changed or added

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 93.18182% with 3 lines in your changes missing coverage. Please review.

Project coverage is 95.64%. Comparing base (462c949) to head (aa34927).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/Providers/SessionCredentialsProvider.php	82.35%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master      #34      +/-   ##
============================================
- Coverage     97.59%   95.64%   -1.95%     
- Complexity      559      574      +15     
============================================
  Files            30       31       +1     
  Lines          1660     1768     +108     
============================================
+ Hits           1620     1691      +71     
- Misses           40       77      +37     

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