Track handles in channel_read

[ipetr0v]

This change fixes a bug where channel_read was tracking the channel on which it read a message instead of tracking the received handles.

Checklist

• Pull request affects core Oak functionality (e.g. runtime, SDK, ABI)
  • I have checked that these tests are run by Cloudbuild

[daviddrysdale]

BTW, this is also fixed as part of #894, but if it's blocking you we can certainly put this PR in in the meanwhile.

[ipetr0v]

It is blocking #874 and I can't run gRPC server for debugging.

[github-actions]

Reproducibility index:

0ceecd06461fc8907a319182fe57bd5053d83a0cff17388fabfcb2788468ba78  ./target/wasm32-unknown-unknown/release/abitest_0_frontend.wasm
8c2289c1807cd428d74e578c9104508157b0210d6e4b949f8c3c1a087e093a65  ./target/wasm32-unknown-unknown/release/abitest_1_backend.wasm
4845016281f0aa8762230a62890de065aafad4386f3e1ce84b301fc7995abdbd  ./target/wasm32-unknown-unknown/release/aggregator.wasm
19254f86fa9ffffc0aaaa3d89ae54f7805d437f99b9735e6592af653b626e6bf  ./target/wasm32-unknown-unknown/release/chat.wasm
78dcafbfe3ee1049d61bebfb2d94f1cfcf8b975d090f45f245a8fa81ec0945d8  ./target/wasm32-unknown-unknown/release/hello_world.wasm
a2d6a8fb4fec82d7184e396730241a1571be2cca08513e3219cd61b74fb01990  ./target/wasm32-unknown-unknown/release/machine_learning.wasm
485be208a04c87a2fc52d8114a237dc018c8dfc54e48a8a2512b8b933f5df863  ./target/wasm32-unknown-unknown/release/private_set_intersection.wasm
c1addfdf140eba447ec35e2f9a8ec246b9a7d36ac11a87556194eea5f0a254f3  ./target/wasm32-unknown-unknown/release/running_average.wasm
29e89b8fe1946b6c88f2b639f8a70b5b26fffb37f9ddcca2f6e1384386a3005d  ./target/wasm32-unknown-unknown/release/translator.wasm