Fix multiple bugs in GDB RP functionality

[MaxDesiatov]

Multiple issues with GDB RP implementation are addressed here:

1. WasmKit not shutting down after debugger client sends a kill packet. We have to use a wrapping withThrowingTaskGroup for existing withThrowingDiscardingTaskGroup to propagate debugger handler cancellation error.
2. isNoAckModeActive set too early in GDBHostCommandDecoder, which led to non-deterministic issues with command decoding.
3. Separate enum BreakpointState within Debugger to properly express its state machine nature and correctly report exit codes of WASI modules to the debugger client.
4. Use of Execution.CurrentMemory.mayUpdateCurrentInstance without the from: parameter, which means we no longer go through an early return path and now correctly set linear memory instance when resuming from a breakpoint.
5. Fixed OOB in binary search implementation in DebuggerInstructionMapping, where we had to peek outside of an array slice and use Array's self instead of local slice.