R1:9dde415884aa

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.