Release runtime 0.12 and extension 0.11

[calavera]

Description of changes:

Runtime:

• Relax Diagnostic trait implementation (this is a big change, so I rather have a minor release instead of a patch)
• Fix issues creating parent tracing spans

Extension:

• Add account id response extension

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• I confirm that my contribution is made under the terms of the Apache 2.0 license.
• I confirm that I've made a best effort attempt to update all relevant documentation.