This change adds support to the `PerforceParser` for applying binary files as part of changes. The most basic part of this is just the implementation of the add/move/delete methods, but while working on this I discovered that patching for Perforce was broken in a variety of ways: * We've traditionally relied on the `patch` command to handle opening the relevant files, and we still do, but it now opens and edits them in a way which requires running `p4 reconcile`. This command has been added to the end of the patch sequence. * `apply_patch_for_empty_files` would use a regex to pull out filenames from the diff that then got passed to `p4 add` or `p4 delete`, but that regex only stripped off a leading "//" and did not map filenames to client names. It seems like in some cases Perforce was clever enough to know that "depot/something/..." really meant "//depot/something/...", but that depended highly on what that depot was called and what the client mapping was set up to look like. I've changed it to map the depot filenames to local first. * `apply_patch_for_empty_files` was only being called in the case that the patch entirely failed to apply, meaning we had a change that comprised *only* empty files. Patches with a mix of empty and non-empty file changes would apply the non-empty ones and skip the rest. The fix for this issue is actually inside /r/14711, which reorganizes the top-level patching process to always call this method when needed. Testing Done: - Ran unit tests. - Applied a variety of patches that included mixes of empty, non-empty, and binary files.