Initial commit (#10454)

This PR is a precursor to the recovery logic refactor work (KAFKA-12553).

I've renamed the file: core/src/test/scala/unit/kafka/log/LogUtils.scala to core/src/test/scala/unit/kafka/log/LogTestUtils.scala. Also I've renamed the underlying lass from LogUtils to LogTestUtils. This is going to help avoid a naming conflict with a new file called LogUtils.scala that I plan to introduce in core/src/main/scala/kafka/log/ as part of the recovery logic refactor. The new file will also contain a bunch of static functions.

Tests:
Relying on existing tests to catch regressions (if any) since this is a simple change.

Reviewers: Satish Duggana <satishd@apache.org>, Dhruvil Shah <dhruvil@confluent.io>, Jun Rao <junrao@gmail.com>

core/src/test/scala/unit/kafka/log/LogSegmentTest.scala

@@ -43,7 +43,7 @@ class LogSegmentTest {
   def createSegment(offset: Long,
                     indexIntervalBytes: Int = 10,
                     time: Time = Time.SYSTEM): LogSegment = {
-    val seg = LogUtils.createSegment(offset, logDir, indexIntervalBytes, time)
+    val seg = LogTestUtils.createSegment(offset, logDir, indexIntervalBytes, time)
     segments += seg
     seg
   }

core/src/test/scala/unit/kafka/log/LogSegmentsTest.scala

@@ -32,7 +32,7 @@ class LogSegmentsTest {
   private def createSegment(offset: Long,
                     indexIntervalBytes: Int = 10,
                     time: Time = Time.SYSTEM): LogSegment = {
-    LogUtils.createSegment(offset, logDir, indexIntervalBytes, time)
+    LogTestUtils.createSegment(offset, logDir, indexIntervalBytes, time)
   }
 
   private def assertEntry(segment: LogSegment, tested: java.util.Map.Entry[java.lang.Long, LogSegment]): Unit = {

core/src/test/scala/unit/kafka/log/LogUtils.scala → core/src/test/scala/unit/kafka/log/LogTestUtils.scala

@@ -22,7 +22,7 @@ import java.io.File
 import org.apache.kafka.common.record.FileRecords
 import org.apache.kafka.common.utils.Time
 
-object LogUtils {
+object LogTestUtils {
   /**
     *  Create a segment with the given base offset
     */