verify the plugin zip in github workflows

[shalom938]

in the new intellij platform gradle plugin jetbrains changed the packaging of the plugin zip and the jars in lib. before the new plugin the main plugin jar and the plugin modules were packaged individually into the lib forlder of the zip. the new plugin has a ComposedJarTask that merges all the plugin classes into one jar and this one jar is packaged in the plugin zip. when building locally the jar is for example build/libs/digma-intellij-plugin-2.0.342+233.jar this poses a new risk of files not packaged correctly. for example we have some properties files, service files, and maybe other files in the various modules. we can add verification that all our files are packaged correctly. see for example the step 'Find posthog url', we can unzip the jar and verify that all our non source files are there.