Remove calls to deprecated url.parse

[acdibble]

Fixes #1357.

url.parse and the legacy Node.js Url object were deprecated in Node 12.

By replacing it with the WHATWG URL API, username and password parsing comes for free. Additionally, uses of the query property had to be changed to use the URLSearchParams object.

[acdibble]

@sidorares , I've fixed the parsing and added a new test to validate the behavior. Let me know if there is anything else I can do to help get this merged in.

[sidorares]

@acdibble I think your editor config is slightly different to what's used here, can you discard commits unrelated to your main change ( replacing url.parse with URL )? appveyor build fails because of lint errors

[acdibble]

@sidorares , I think one of the commit hooks changed some stuff. It seems like my local ESLint is in conflict with Appveyor's:

$ npx eslint .

~/node-mysql2/examples/promise-co-await/co.js
  17:9   error  Unexpected function expression  prefer-arrow-callback
  20:10  error  Unexpected function expression  prefer-arrow-callback

~/node-mysql2/examples/ssl/rds-ssl.js
  14:45  error  Unexpected function expression  prefer-arrow-callback

~/node-mysql2/examples/ssl/select-over-ssl.js
  19:34  error  Unexpected function expression  prefer-arrow-callback
  21:49  error  Unexpected function expression  prefer-arrow-callback

~/node-mysql2/tools/generate-charset-mapping.js
  33:30  error  Unexpected function expression   prefer-arrow-callback
  46:17  error  Unexpected string concatenation  prefer-template

✖ 7 problems (7 errors, 0 warnings)
  7 errors and 0 warnings potentially fixable with the `--fix` option.

I've reverted those changes so hopefully the build is green this time.

[sidorares]

thanks @acdibble !