* Move all pki-verification calls from sdk-Verify() to pki-specific
VerifyCertifcate(...); update sdk-Verify to allow multiple chains,
but validate that at least one of those chains is valid.
* Updates to Validate on Parse PEMBlock, so that a single cert or a single key parses (test fixes).
* Add changelog.
* Make test certificate expire in a while, not at linux epoch.
* Remove duplicate code.
* Fix header file + go mod tidy.
* Updates based on review.
