1224: Fixed compatibility issues by updating icon constants

[makzef]

Description (*)
Fixed several compatibility issues related to usage of unavailable icon constants.
In this PR was used icon constants that compatible with new version of IDE (currently Intellij IDEA 2022.3 EAP).

Some details about updated icons. For screenshots previous icons I use stable 4.4.0 version of plugin and new icons marked as 4.4.1-develop :

1. PhpIcons.CLASS_ICON → AllIcons.Nodes.Class
   
   

2. PhpIcons.XML_TAG_ICON → AllIcons.Nodes.Tag
   
   

3. PhpIcons.Php_icon → PhpIcons.PhpIcon
   PhpIcons.Php_icon is deprecated, if we look at the code we can see that PhpIcons.Php_icon just refers to PhpIcons.PhpIcon.
   
   

Also made some code style improvements (checkstyles, etc.).

Fixed Issues (if relevant)

1. Fixes Investigate and fix if possible compatibility problems with the PS 2022.3 (EAP) #1224

Questions or comments

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with integration/functional tests (if applicable)
• All automated tests passed successfully (all builds are green)

[bohdan-harniuk]

Hello, @makzef !
Great work!
Thank you!