Improve log file output, upload artifact

[swissspidy]

Fixes #226

[swissspidy]

Output looks as follows btw:

  FILE: hello.php
  [{"line":0,"column":0,"type":"ERROR","code":"plugin_header_no_license","message":"Missing \"License\" in Plugin Header. Please update your Plugin Header with a valid GPLv2 (or later) compatible license.","docs":"https:\/\/developer.wordpress.org\/plugins\/wordpress-org\/common-issues\/#no-gpl-compatible-license-declared"},{"line":49,"column":31,"type":"ERROR","code":"WordPress.WP.AlternativeFunctions.rand_mt_rand","message":"mt_rand() is discouraged. Use the far less predictable wp_rand() instead.","docs":""},{"line":62,"column":9,"type":"ERROR","code":"WordPress.Security.EscapeOutput.OutputNotEscaped","message":"All output should be run through an escaping function (see the Security sections in the WordPress Developer Handbooks), found '__'.","docs":"https:\/\/developer.wordpress.org\/apis\/security\/escaping\/#escaping-functions"},{"line":62,"column":62,"type":"ERROR","code":"WordPress.WP.I18n.TextDomainMismatch","message":"Mismatched text domain. Expected 'hello-dolly-copy' but got 'hello-dolly'.","docs":"https:\/\/developer.wordpress.org\/plugins\/internationalization\/how-to-internationalize-your-plugin\/"},{"line":63,"column":9,"type":"ERROR","code":"WordPress.Security.EscapeOutput.OutputNotEscaped","message":"All output should be run through an escaping function (see the Security sections in the WordPress Developer Handbooks), found '$lang'.","docs":"https:\/\/developer.wordpress.org\/apis\/security\/escaping\/#escaping-functions"},{"line":64,"column":9,"type":"ERROR","code":"WordPress.Security.EscapeOutput.OutputNotEscaped","message":"All output should be run through an escaping function (see the Security sections in the WordPress Developer Handbooks), found '$chosen'.","docs":"https:\/\/developer.wordpress.org\/apis\/security\/escaping\/#escaping-functions"}]
  
  FILE: readme.txt
  [{"line":0,"column":0,"type":"ERROR","code":"no_plugin_readme","message":"The plugin readme.txt does not exist.","docs":""}]