Stop bundling palantir's platform library in the IDEA plugin

The IDEA plugin declared com.palantir.gradle.utils:platform without
using it: nothing in its sources, nor in the jdk-bootstrap and SPI
modules it bundles, refers to the library. Dropping it takes four jars
out of the plugin zip: platform, exec, providers and
safe-exec-commandline.

Author: abashev

open-java-format-idea-plugin/build.gradle

@@ -75,7 +75,6 @@ dependencies {
 
     implementation project(':open-java-format-jdk-bootstrap')
     implementation libs.caffeine
-    implementation libs.palantir.platform
 
     formatter project(':open-java-format')