minor: patch_paser.py: add __repr__ for .*Map classes
minor: patch_paser.py: add __repr__ for .*Map classes

We're currently having issues where the comments line numbers are
slightly off (always seem to be a 1-2 below where they should be).

So make it easier to debug what's going wrong by adding these to dump
the intermediate datastructures.

Example output derived from ./src/test_data/fake_patch_with_replies/

RawLineToGerritLineMap(
  PatchFileLineMap(name=file range=(13, 23)
  chunks=
    PatchFileLineMap(side=, offset=-11, range=(13, 15))
    PatchFileLineMap(side=b, offset=-11, range=(16, 16))
    PatchFileLineMap(side=, offset=-11, range=(17, 18))
    PatchFileLineMap(side=, offset=-11, range=(19, 23)))
)

google/lkml-gerrit-bridge