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This consolidates the certificate parsing from various places in
verify_certificate_chain.cc into a single class that pre-parses all the
important information.
The relevant places are all changed to use the new ParsedCertificate
class, and TrustStore is separated into its own file.

BUG=410574

Review-Url: https://codereview.chromium.org/1976433002
Cr-Commit-Position: refs/heads/master@{#397863}