Introduce a new Admin API to change SFT implementation

Introduced two admin methods: void modifyTableStoreFileTracker(TableName, String) throws IOException; void modifyColumnFamilyStoreFileTracker(TableName, byte[], String) throws IOException; You can use these two methods to change the store file tracker implementation for a table or a family, where you just need to specify the final store file tracker implementation, and do not need to take care of the 'migration' intermediate state, at master side we will take care of it for you.