replace all uses of pem with pem-rfc7468 crate

[flihp]

No description provided.

[flihp]

the dice-mfg utility hasn't been tested yet, the tmpl stuff works as expected

[flihp]

this should be split into 2 PRs: one for the tmpl stuff, the other for dice-mfg. The tmpl work is low risk (if I break it no one else will care) and has already been lightly tested. The dice-mfg stuff needs more / better testing and that will be happening over the next ~2 months as we push the online-signing bits forward. When that's happening we can test the PEM bits too.

[flihp]

#178 replaced this library in the dice-cert-tmpl crate. The remaining work here needs to be rebased and tested.

[flihp]

and now it just needs to be tested

[flihp]

Finally had another task that required doing front to back testing of the mfg process. Now that verifier-cli works(ish) we can use that as a test case that analyzes the platform identity data. This works as expected.