fix(bindings): remove mutation behind Arc

[jmayclin]

Description of changes:

• don't mutate item behind immutable ref
• tie lifetime to CertificateChainHandle

In connection.rs, we essentially mutate a CertificateChainHandle which is behind Arc<CertificateChainHandle>. This does not seem correct.

If you have a reference &T, then normally in Rust the compiler performs optimizations based on the knowledge that &T points to immutable data. Mutating that data, for example through an alias or by transmuting a &T into a &mut T, is considered undefined behavior.
UnsafeCell docs

Additionally, the most accurate place to tag the lifetime is on the underlying CertificateChainHandle, which already has the is_owned field.

Call-outs:

This refactor is being done to simplify the addition of an application-level CertificateChainContext.

Testing:

This is a refactor. All existing tests should continue to pass.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.