RefreshAppend should update appended/deleted files list in metadata

[apoorvedave1]

Describe the issue

Prerequisite PR: PR #170
(PR #170 updates IndexLogEntry and adds appended property to source properties).

The above mentioned PR will introduce appended and deleted list of files in metadata. The current RefreshAppendAction, as per this ongoing PR #163 , does not take into account these metadata values yet. Make sure to update these values as required:

1. clean up appended files if they were picked for index creation in RefreshAppendAction
2. If deleted list remains untouched, keep the deleted files list as it is in the new log entry.

To Reproduce

1. User creates an index on some data e.g., "/path/to/dataset/".
2. User deletes some files from the original data and adds some new files under "/path/to/dataset/".
3. User sets spark.hyperspace.index.refresh.append.enabled flag to true and calls refresh to update index by creating index on appended files.
   Once refresh finishes successfully, a newer version of index is created and latest metadata shows updated signature and empty appended/deleted files. Make sure the deleted files list is same as previous log entry.

Expected behavior

After refresh: appended and deleted files list in index metadata is correctly handled.

Environment

[apoorvedave1]

closed by #191