Rename `TestConfigSections` to `PluginType` and store it on `TestSuite`

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We have com.saveourtool.save.core.config.TestConfigSections in save-cli, which stores in common module. We store a simple name of class of plugin in pluginName in com.saveourtool.save.entities.Test. We don't have access to plugin classes in common module, that why we store it as String.

We can rename TestConfigSections to PluginType and store is on TestSuite instead of pluginName