Oauth2 strategy: query parameters in x-www-form-urlencoded

[visyone]

Please read and mark the following check list before creating a pull request:

• I read and followed the CONTRIBUTING.md guide.

Short description of what this resolves:

According RFC 6749, all oauth2 flow sends parameters in x-www-form-url-encoded format

[visyone]

Hi, there is a chance that this changes will be merged in master and available in next release?

[codecov]

Codecov Report

Merging #1066 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1066      +/-   ##
==========================================
+ Coverage    76.6%   76.62%   +0.01%     
==========================================
  Files         200      200              
  Lines        6062     6066       +4     
  Branches      465      467       +2     
==========================================
+ Hits         4644     4648       +4     
  Misses       1308     1308              
  Partials      110      110

Impacted Files	Coverage Δ
...ramework/auth/strategies/oauth2/oauth2-strategy.ts	84.56% <100%> (+0.42%)	⬆️