sync: support cancel_rx in ttrpc context

[yuqitao]

Fixes: https://github.com/containerd/ttrpc-rust/issues/180

[codecov[bot]]

Codecov Report

Patch coverage has no change and project coverage change: -0.30 :warning:

Comparison is base (e94bb9f) 24.47% compared to head (f9bff19) 24.17%.

:exclamation: Current head f9bff19 differs from pull request most recent head 100cff9. Consider uploading reports for the commit 100cff9 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #197 +/- ## ========================================== - Coverage 24.47% 24.17% -0.30% ========================================== Files 17 17 Lines 2521 2552 +31 ========================================== Hits 617 617 - Misses 1904 1935 +31 ``` | [Impacted Files](https://app.codecov.io/gh/containerd/ttrpc-rust/pull/197?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=containerd) | Coverage Δ | | |---|---|---| | [src/sync/server.rs](https://app.codecov.io/gh/containerd/ttrpc-rust/pull/197?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=containerd#diff-c3JjL3N5bmMvc2VydmVyLnJz) | `0.00% <0.00%> (ø)` | | | [src/sync/utils.rs](https://app.codecov.io/gh/containerd/ttrpc-rust/pull/197?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=containerd#diff-c3JjL3N5bmMvdXRpbHMucnM=) | `0.00% <ø> (ø)` | |

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[Tim-Zhang]

Good catch @yuqitao, @lifupan PTAL.

[yuqitao]

@lifupan @jsturtevant PTAL.

[yuqitao]

@Tim-Zhang The CI seems to have some wired error, could you help solving it please?