Add more Subversion unit tests

Summary:
Ref T4327. Adds additional SVN tests to cover:

  - replacing a file with a file;
  - replacing a file with a directory;
  - removing a directory with files in it;
  - adding a directory with files;
  - copying a directory and adding and deleting files inside it.

Test Plan: Ran unit tests. One of these has a slightly irregular parse, see inline.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4327

Differential Revision: https://secure.phabricator.com/D8017