IntelliJ: exclude some directories from being indexed (#720)

When editing `.gitignore`, IntelliJ warns about a couple directories being ignored but not excluded from being indexed and searched. This change ignores the mentioned directories, except the one for DW, which is going away with #469.

Author: snazy

build-logic/src/main/kotlin/polaris-root.gradle.kts

@@ -44,6 +44,19 @@ if (System.getProperty("idea.sync.active").toBoolean()) {
       isDownloadJavadoc = false // was 'true', but didn't work
       isDownloadSources = false // was 'true', but didn't work
       inheritOutputDirs = true
+
+      excludeDirs =
+        excludeDirs +
+          setOf(
+            projectDir.resolve("build-logic/.kotlin"),
+            projectDir.resolve("integration-tests/build"),
+            projectDir.resolve("site/resources/_gen"),
+            projectDir.resolve("site/build"),
+            projectDir.resolve("logs"),
+            projectDir.resolve("polaris-venv"),
+            projectDir.resolve(".idea"),
+          ) +
+          allprojects.map { prj -> prj.layout.buildDirectory.asFile.get() }
     }
 
     project.settings {