Lets the client repository make 'git cl format' use the
'--full' option by default. This solves issues when using less
common clang-format options that don't behave well with small
diffs. For example, AlignConsecutiveAssignments.

This is a replacement for the 'diff-lines-of-context' setting.

Bug: angleproject:4003
Change-Id: I81dc3b4992a7420e7235da88ec78e51ec4c0d24f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1879148Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>