Add c10d filestore functionality to the current c10d_rendezvous_backend (#59719)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59719
Added filestore functionality to the c10d backend. FileStore will create a temporary file in the /tmp directory to use if it is selected as the store type. Appropriate tests were added as well.
FileStore was modified to expose the path field for testing. It was also modified so that the numWorkers field in the constructor is optional (defaulting to -1). A negative value indicates there is not a fixed number of workers. In this case, the file is not attempted to be cleaned at the end.
Test Plan: Unit tests for creating a c10d backend with filestore and simple error handling.
Reviewed By: cbalioglu, H-Huang
Differential Revision: D28997436
fbshipit-source-id: 24c9b2c9b13ea6c947e8b1207beda892bdca2217
