Fix plugin not applying plugins as intended

[ENDERZOMBI102]

when the architectury plugin is applied, it tries to apply 4 more plugins ( java, eclipse, idea and org.jetbrains.gradle.plugin.idea-ext ), but the way it was done caused only the last one ( org.jetbrains.gradle.plugin.idea-ext ) to actually apply, as maps cannot contain more than one value for a specific key, this PR fixes this by using the project.pluginManager.apply() method to apply each plugin individually.

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