Various enhancement for Automation Framework

[jacklesotatek]

Solution to export test result into a PDF file (using this piece of code):

It will generate a report file like this one
playwright-report.pdf

Solution to run the test suite on preprod and mainnet config:

• Previous I am using this library to read the config file : https://www.npmjs.com/package/dotenv
  This library it got a cons that it only can read from one .env config file , we cannot read from many env file
• Now I am using this library to read the config file : https://www.npmjs.com/package/cross-env
• This library can read all the config file
  Solution to send a Slack notification if the test is failed:
• I cannot implement a Gmail notification due to it required to provide username/password : https://nodemailer.com/
• Also I cannot upload my Slack webhook URL due to this problem (see picture attached)
  
• This is the result (the testcase are intentionally failed and the failed result is send to myself )
  

Also I did update the README file to reflect these change