THRIFT-5581: use gradle 7 for java/kotlin (#2601)

* upgrade gradle version to 7.4
* migrate from `maven` plugin to `maven-publish` plugin as required for Gradle 7
* add guard to ktfmt, since it can't run with JDK 8

Co-authored-by: Christopher Tubbs <ctubbsii@apache.org>
diff --git a/lib/java/gradle/unitTests.gradle b/lib/java/gradle/unitTests.gradle
index 0f09aa9..db9ad82 100644
--- a/lib/java/gradle/unitTests.gradle
+++ b/lib/java/gradle/unitTests.gradle
@@ -44,14 +44,14 @@
 task deprecatedEqualityTest(type: JavaExec, group: 'Verification') {
     description = 'Run the non-JUnit test suite '
     classpath = sourceSets.test.runtimeClasspath
-    main 'org.apache.thrift.test.EqualityTest'
+    mainClass.set('org.apache.thrift.test.EqualityTest')
     markTaskDone(it)
 }
 
 task deprecatedJavaBeansTest(type: JavaExec, group: 'Verification') {
     description = 'Run the non-JUnit test suite '
     classpath = sourceSets.test.runtimeClasspath
-    main 'org.apache.thrift.test.JavaBeansTest'
+    mainClass.set('org.apache.thrift.test.JavaBeansTest')
     markTaskDone(it)
 }