feat(metagen)!: hostcall transport (#982)

- [x] update docs
- [x] HostcallTransport for fdk_rs/fdk_ts/fdk_py
- [x] Reimpml fdk_py
- [x] MET-815 `QueryGraph` method clash

#### Migration notes

- `fdk_rs`: transport construction is no longer a method on `QueryGraph`
but a set of functions in th `transports` module.
- `fdk_ts`: transport construction is no longer a method on `QueryGraph`
but instead a static method on `Transports` class.
- `fdk_py` now generates all code into `fdk.py`
  - Decorators now use the `handler_{fn_name}` pattern
  - Decorators now expect a second `Ctx` object.
- `Ctx.gql` method now takes `typing.Mapping` instead of raw JSON `str`
- Transport construction is no longer a method on `QueryGraph` but
instead a static method on `Transports` class.

---

- [x] The change comes with new or modified tests
- [ ] Hard-to-understand functions have explanatory comments
- [x] End-user documentation is updated to reflect the change


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

## Summary by CodeRabbit

- **New Features**
- Introduced enhanced GraphQL client transports that support
asynchronous host calls and refined query handling, enabling more robust
queries, mutations, and file upload operations.
- Added new `HostcallPump` class for managing host calls and responses,
improving the handling of asynchronous operations.
- Expanded functionality for handling selections and query construction,
including new types and methods in the `QueryGraph` class.
- Updated `Cargo.toml` configurations to include workspace features for
`metagen-client`, allowing for specific feature activation.
- Adjusted the `typegraphUrl` format in the `hostcallCtx` for improved
communication protocols.

- **Refactors & Chores**
- Streamlined internal architecture by consolidating transport logic and
improving type mapping and dependency management across modules.
- Removed legacy code and enhanced error handling and logging for
increased stability.
- Adjusted paths and target architecture in build scripts for
consistency with updated directory structures.

- **Tests & Documentation**
- Expanded and reorganized test suites to verify the new client and
query graph functionality, with updated configuration options detailed
in the documentation.
- Enhanced test cases for better coverage of new features and
functionalities, including proxy primitives and selection handling.
- Updated test configurations to reflect new dependencies and structural
changes in the codebase.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: Yohe-Am

.ghjk/deno.lock

@@ -977,7 +977,7 @@
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@@ -1762,7 +1762,7 @@
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@@ -1800,7 +1800,7 @@
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@@ -1838,7 +1838,7 @@
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@@ -1876,7 +1876,7 @@
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@@ -1886,7 +1886,7 @@
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