[K/N][test] Eager test group creation based on test roots

This commit adds an option to make test grouping eagerly create larger
groups of tests. Each MetaGroup is created based on the test root the
test file is located in. Test compilation tries to compile all
compatible tests in the group into the final binary/executable.

This grouping strategy allows infrastructure to reduce the number of
produced artifacts, and along with running tests from the same binary,
reduce execution time.

This is a part of ^KT-58928 to implement running tests on iOS devices.

repo/gradle-build-conventions/buildsrc-compat/src/main/kotlin/nativeTest.kt

@@ -28,6 +28,7 @@ private enum class TestProperty(shortName: String) {
     EXECUTION_TIMEOUT("executionTimeout"),
     SANITIZER("sanitizer"),
     SHARED_TEST_EXECUTION("sharedTestExecution"),
+    EAGER_GROUP_CREATION("eagerGroupCreation"),
     TEAMCITY("teamcity");
 
     val fullName = "kotlin.internal.native.test.$shortName"
@@ -197,6 +198,7 @@ fun Project.nativeTest(
             compute(EXECUTION_TIMEOUT)
             compute(SANITIZER)
             compute(SHARED_TEST_EXECUTION)
+            compute(EAGER_GROUP_CREATION)
 
             // Pass whether tests are running at TeamCity.
             computePrivate(TEAMCITY) { kotlinBuildProperties.isTeamcityBuild.toString() }