(fix): add support for TLS certificates pinning

[jaeopt]

Summary

Some applications require support for TLS pinning for extra security. This fix allows opt-in for that feature.

• add opt-in settings (off by default - most applications do not need this)
• embed public root certificates and verify if certs not compromised when pinning is enabled.
• this feature is for iOS only (not supported for tvOS)

Test plan

• Add new unit tests for 4 combinations: {(disabled, good), (enabled, good), (disabled, bad), (enabled, bad)}
• Add FSC test suites

Issues

• OASIS-5056

[coveralls]

Coverage decreased (-76.8%) to 21.397% when pulling b061c71c3a95543284f0a080814a13d8ea63fe0f on jae/pinning into 98f640fe0c40d5e6a683798d94e1d049a7fe4d83 on master.

[jaeopt]

SSL pinning support is put on hold. We'll review the issue and solution again later.