fix(rice-proto): forward TCP AllocateSocket to checklist after gathering

[ShaJaPas]

Summary

• Fix StreamMut::allocated_socket so connectivity-check AllocateSocket requests reach the checklist after local gathering has finished (RFC 6544 TCP ICE).
• Add unit test allocated_socket_reaches_checklist_after_gathering that reproduces the hang without the fix.

Test plan

• cargo test -p rice-proto --no-default-features --features std,rustls allocated_socket_reaches_checklist_after_gathering

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.35%. Comparing base (87c2e94) to head (bbfc1b4).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #167      +/-   ##
==========================================
+ Coverage   86.22%   86.35%   +0.12%     
==========================================
  Files          38       38              
  Lines        6681     6678       -3     
==========================================
+ Hits         5761     5767       +6     
+ Misses        920      911       -9     

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[ystreet]

Thanks for the PR. LGTM once the style and clippy issues are fixed.

[ystreet]

clippy is not happy :)

libturn_client_rustls-511e093895477c44.rmeta -L native=/home/runner/work/librice/librice/target/debug/build/aws-lc-sys-31a39d28b72ae5b8/out -L native=/home/runner/work/librice/librice/target/debug/build/ring-e128f643502bc982/out`
error: this loop could be written as a `while let` loop
    --> rice-proto/src/conncheck.rs:2547:17
     |
2547 | /                 loop {
2548 | |                     let Some(data) = tcp_buffer.pull_data() else {
2549 | |                         break;
2550 | |                     };
...    |
2583 | |                         .unwrap();
2584 | |                 }
     | |_________________^ help: try: `while let Some(data) = tcp_buffer.pull_data() { .. }`
     |
     = help: for further information visit https://rust-lang.github.io/rust-clippy/rust-1.96.0/index.html#while_let_loop
     = note: `-D clippy::while-let-loop` implied by `-D warnings`
     = help: to override `-D warnings` add `#[allow(clippy::while_let_loop)]`

[ShaJaPas]

@ystreet I've checked locally, all check now should pass :)