Add Gradle wrappers for Kotlin tests

This avoids tests' behaviour changing due to environmental Gradle version changes

Author: smowton

java/ql/integration-tests/posix-only/kotlin/gradle_groovy_app/.gitattributes

@@ -0,0 +1,6 @@
+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# These are explicitly windows files and should use crlf
+*.bat           text eol=crlf
+

java/ql/integration-tests/posix-only/kotlin/gradle_groovy_app/gradle/wrapper/gradle-wrapper.jar

@@ -0,0 +1,6 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.6-bin.zip
+networkTimeout=10000
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

java/ql/integration-tests/posix-only/kotlin/gradle_groovy_app/gradle/wrapper/gradle-wrapper.properties

@@ -1,4 +1,7 @@
+import platform
 from create_database_utils import *
 
-run_codeql_database_create(["gradle build --no-daemon --no-build-cache"], lang="java")
-runSuccessfully(["gradle", "clean"])
+gradle_cmd = "gradlew.bat" if platform.system() == "Windows" else "./gradlew"
+
+run_codeql_database_create(
+    ["%s build --no-daemon --no-build-cache" % gradle_cmd], lang="java")

java/ql/integration-tests/posix-only/kotlin/gradle_groovy_app/gradlew

@@ -0,0 +1,6 @@
+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# These are explicitly windows files and should use crlf
+*.bat           text eol=crlf
+

java/ql/integration-tests/posix-only/kotlin/gradle_groovy_app/gradlew.bat

@@ -0,0 +1,6 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.6-bin.zip
+networkTimeout=10000
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists