HBASE-22771 [HBCK2] fixMeta method and server-side support

This is a first cut at this patch. Implements hold fixing only
currently.

Add a fixMeta method to Hbck Interface.

M hbase-server/src/main/java/org/apache/hadoop/hbase/master/CatalogJanitor.java
 Bug fix. If hole is on end of last table, I wasn't seeing it.

A hbase-server/src/main/java/org/apache/hadoop/hbase/master/MetaFixer.java
 Add a general meta fixer class. Explains up top why this stuff doesn't
 belong inside MetaTableAccessor.

M hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
 Break out the filesystem messing so don't have to copy it nor do more
 than is needed doing fixup for Region holes.

M hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionFileSystem.java
 Change behavious slightly. If directory exists, don't fail as we did
 but try and keep going and create .regioninfo file if missing (or
 overwrite if in place). This should make it idempotent. Can rerun
 command. Lets see if any repercussions in test suite.

A hbase-server/src/test/java/org/apache/hadoop/hbase/master/TestMetaFixer.java
 Add test.

Signed-off-by: Zheng Hu <openinx@gmail.com>
Signed-off-by: Guanghao Zhang <zghao@apache.org>

hbase-server/src/main/java/org/apache/hadoop/hbase/master/MasterRpcServices.java

@@ -182,8 +182,8 @@
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.EnableTableResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ExecProcedureRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ExecProcedureResponse;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.FixMetaResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.FixMetaRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.FixMetaResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.GetClusterStatusRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.GetClusterStatusResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.GetCompletedSnapshotsRequest;

hbase-server/src/test/java/org/apache/hadoop/hbase/master/TestMetaFixer.java

@@ -25,9 +25,7 @@
 import org.apache.hadoop.hbase.HConstants;
 import org.apache.hadoop.hbase.MetaTableAccessor;
 import org.apache.hadoop.hbase.TableName;
-import org.apache.hadoop.hbase.client.Delete;
 import org.apache.hadoop.hbase.client.RegionInfo;
-import org.apache.hadoop.hbase.client.Table;
 import org.apache.hadoop.hbase.testclassification.LargeTests;
 import org.apache.hadoop.hbase.testclassification.MasterTests;
 import org.junit.AfterClass;