HBASE-23055 Alter hbase:meta (#1043)

Make hbase:meta region schema dynamic.

Patch has been under development a good while and its focus has changed
a few times so its bloated with fixup from older versions.

M hbase-server/src/main/java/org/apache/hadoop/hbase/master/TableStateManager.java
M hbase-client/src/main/java/org/apache/hadoop/hbase/zookeeper/ZNodePaths.java
 Shut down access to internals and removed unused methods.

M hbase-server/src/main/java/org/apache/hadoop/hbase/master/procedure/EnableTableProcedure.java
 Cleanup/refactor section on replica-handling.

M hbase-server/src/main/java/org/apache/hadoop/hbase/util/FSTableDescriptors.java
 Get hbase:meta schema from filesystem rather than from hard-coding.
29 files changed