File Existence Check

[What if we are trying to close a file that could not be created for writing?](https://github.com/bcgov-c/data-linking/blob/develop-2.0/lib/cdi-linking/cdilinker/linker/chunked_dedup.py#L228)

Initially I was confused regarding the purpose of statements like the above. After talking to Khalegh I understood that he is trying to make sure that the file that he will need soon exists.

Another similar one : https://github.com/bcgov-c/data-linking/blob/develop-2.0/lib/cdi-linking/cdilinker/linker/chunked_dedup.py#L261

There are couple of similar ones in https://github.com/bcgov-c/data-linking/blob/develop-2.0/lib/cdi-linking/cdilinker/linker/chunked_link.py as well.