Subinvoke resolution context

[nerfZael]

Here is the analogous PR in the JS client: polywrap/javascript-client#3

This PR implements resolution context passing to subinvocations. This way, context can be tracked across all nested wrapper calls. This allows for full resolution history tracking, as well as preventing potential recursive resolutions when using resolver extension wrappers.

Changes:

• UriResolutionContex.createSubContext(): History is not passed to the sub context and is instead left to the parent to control how it integrates with the parent history.
• Subinvoker: A new client invoker wrapper structure used as the invoker passed to wrappers. This "Subinvoker" includes the resolution context into the subinvocation (unlike in the JS version where it is done through wrappers state in the wasm wrapper and through client override in the plugin wrapper. This will also be changed in the JS client to mimick the Rust version).
• PolywrapClient: instead of passing the resolution context to the load wrapper and invocation processes, seperate sub contexts are created for them. This allows for users to track the load and invocation processes separately