[cdc_rsync] Add integration tests (#42)

[cdc_rsync] Add integration tests

This CL adds Python integration tests for cdc_rsync. To run the tests,
you need to supply a Linux host and proper configuration for cdc_rsync
to work:

  set CDC_SSH_COMMAND=C:\path\to\ssh.exe <args>
  set CDC_SCP_COMMAND=C:\path\to\scp.exe <args>
  C:\python38\python.exe -m integration_tests.cdc_rsync.all_tests --binary_path=C:\full\path\to\cdc_rsync.exe --user_host=user@host

Ran the tests and made sure they worked.

.gitignore

@@ -12,3 +12,4 @@ dependencies
 .qtc_clangd
 bazel-*
 user.bazelrc
+*.pyc