Certificate Transparency Tests

[lgarron]

In particular, for this change I could use test cases for invalid and unrecognized SCTs.

[lgarron]

From the Chromium CL, here are existing examples:

• DV, no SCT: https://garron.net/
• DV, SCT: https://embed.ct.digicert.com/
• EV, no SCT: https://www.mozilla.org/
• EV, SCT: https://www.bankofamerica.com/

[lgarron]

Note: we are already preloaded for expect-ct as a test.

[lgarron]

For some changes that I'm working on, I could use:

• Invalid SCTs.
• SCTs from unknown (bogus) logs.