add signQiniuAuthorization

[lihsai0]

https://developer.qiniu.com/kodo/1201/access-token

[codecov]

Codecov Report

Merging #373 (6bf87f2) into master (e036cb7) will increase coverage by 0.35%.
The diff coverage is 95.00%.

@@            Coverage Diff             @@
##           master     #373      +/-   ##
==========================================
+ Coverage   88.40%   88.76%   +0.35%     
==========================================
  Files          21       21              
  Lines        1553     1593      +40     
==========================================
+ Hits         1373     1414      +41     
+ Misses        180      179       -1     

Impacted Files	Coverage Δ
src/Qiniu/Auth.php	90.90% <95.00%> (+5.72%)	⬆️

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