autotest: Use TPM and PEM blobs instead of flat files in 802.1x

Install client credentials in the TPM and use those for the certificate
and key parameters in EAP config.  Make use of the CACertPEM parameter
to pass the CA certifcate to shill as a raw PEM blob.  This moves our
tests into a world where the paths exercised by Chrome and the paths
exercised by the tests will be the same once Chrome makes the necessary
multiprofile changes.

TEST=Both wifi_dynamicWEP and wifi_check1x_WPA consume this logic and
remain passing.
BUG=chromium:256351
CQ-DEPEND=CL:60831

Change-Id: Ib06784c861600c4a23622d08102f36c7dfd164dd
Reviewed-on: https://gerrit.chromium.org/gerrit/61126
Commit-Queue: Christopher Wiley <wiley@chromium.org>
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Tested-by: Christopher Wiley <wiley@chromium.org>
4 files changed