chore: simplify gitignore: exclude whole .idea/ directory

.gitignore

-# Created by .ignore support plugin (hsz.mobi)
-### JetBrains template
-# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio and WebStorm
-# Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
-
-# User-specific stuff
-.idea/**/workspace.xml
-.idea/**/tasks.xml
-.idea/**/dictionaries
-.idea/**/shelf
-
-# Sensitive or high-churn files
-.idea/**/dataSources/
-.idea/**/dataSources.ids
-.idea/**/dataSources.local.xml
-.idea/**/sqlDataSources.xml
-.idea/**/dynamic.xml
-.idea/**/uiDesigner.xml
-.idea/**/dbnavigator.xml
-
-# Gradle
-.idea/**/gradle.xml
-.idea/**/libraries
-
-# CMake
-cmake-build-debug/
-cmake-build-release/
-
-# Mongo Explorer plugin
-.idea/**/mongoSettings.xml
-
-# File-based project format
-*.iws
-
-# IntelliJ
-out/
-
-# mpeltonen/sbt-idea plugin
-.idea_modules/
-
-# JIRA plugin
-atlassian-ide-plugin.xml
-
-# Cursive Clojure plugin
-.idea/replstate.xml
-
-# Crashlytics plugin (for Android Studio and IntelliJ)
-com_crashlytics_export_strings.xml
-crashlytics.properties
-crashlytics-build.properties
-fabric.properties
-
-# Editor-based Rest Client
-.idea/httpRequests
+.idea