tree ee29887dd9f647702478d12d9c0c9e7df6ee8f57
parent e48e9c255817149516cec96356db6ceb81f78067
author Youssef Elghareeb <ghareeb@google.com> 1603377163 +0200
committer Youssef Elghareeb <ghareeb@google.com> 1605882954 +0100

Add the git file diff cache

The new git file diff cache computes the pure git diff for a single file
path according to a git tree diff. The output entity contains:
  1) List of edits (modified regions) of the file.
  2) Old and new file paths.
  3) Old and new blob object IDs for the file in git.
  4) Change type (file is added or deleted or modified, etc...).
  5) Patch type (whether the file is unified or binary).
  6) File mode.

The cache also returns an empty git FileDiff if the requested file
path does not exist among the set of modified files between the 2
commits identified by their tree IDs in the cache key.

Change-Id: Ia278881c0f5bd71a82ea6863653ae52eb1c3ad0b