Add YAPF style file for autotests

Based on pep8 with custom indentation as described here:
https://chromium.googlesource.com/chromiumos/third_party/autotest/+/master/docs/coding-style.md

BUG=None
TEST=Verified that indentation looks correct

Change-Id: Ia199b761da879d26ae19bead24812530045266d3
Reviewed-on: https://chromium-review.googlesource.com/939463
Commit-Ready: ChromeOS CL Exonerator Bot <[email protected]>
Tested-by: Lutz Justen <[email protected]>
Reviewed-by: Katherine Threlkeld <[email protected]>
diff --git a/.style.yapf b/.style.yapf
new file mode 100644
index 0000000..e36cf68
--- /dev/null
+++ b/.style.yapf
@@ -0,0 +1,3 @@
+[style]
+based_on_style = pep8
+continuation_indent_width = 8