Add junit-platform-launcher dependency

Update `build.gradle` files to ensure that `junit-platform-launcher` is
a `testRuntimeOnly` dependency. This ensures that tests can be run from
Eclipse.

Closes gh-25074

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/build.gradle

@@ -31,6 +31,8 @@ dependencies {
 	testImplementation("org.junit.jupiter:junit-jupiter")
 	testImplementation("org.mockito:mockito-core")
 	testImplementation("org.zeroturnaround:zt-zip:1.13")
+
+	testRuntimeOnly("org.junit.platform:junit-platform-launcher")
 }
 
 sourceSets {