Following will be the part of this ticket:

• Configure the S3 store to accept a local directory as a cache location.
• AWS bucket conn class will get a new function, to check if an object exists. Add a relevant unit test.
• The above function will be used to implement S3 file system's WT_FILE_SYSTEM.fs_exist function. Update the s3_store python test following the file check from test_tiered06.py
• The file exists check should check the cache first for the file, if not check on the S3 store.
• Add relevant statistics