Basic implementation of ACP agent interface using Amazon Q CLI agent

[erbenmo]

Description of changes:
Basic implementation of ACP agent interface using Amazon Q CLI agent

The following features are supported:
- New Session setup ("session/new")
- Basic chat ("session/prompt" & "session/update")
- Using built-in tool like fs_read and fs_write ("tool_call")
- Request tool call permission ("session/request_permission")

We use Symposium ACP as it provides a nicer interface to write non-blocking ACP agent

The main method is handle_prompt_request:
- submit the request to the agent
- poll agent update events, convert them to ACP events, and send them back to ACP client
- tell ACP client that the request is completed

You can test this implementation using acp_client: cargo run -p agent -- acp-client ./target/debug/agent

Testing:

~/Documents/Work/2025/Project/UI/amazon-q-developer-cli $ cargo run -p agent -- acp-client ./target/debug/agent
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 1.43s
     Running `target/debug/agent acp-client ./target/debug/agent`
ACP Test Client - Type messages to send to agent (Ctrl+C to exit)
> hey how are you doing?
Agent: I
Agent: 'm doing well, thanks for asking! I'm
Agent:  here and ready to help you with AWS
Agent:  services, development tasks, or anything
Agent:  else you need assistance with. What
Agent:  can I help you with today?
> can you reverse a linked list and write it to reverse_list.py
Agent: I'll create
Agent:  a minimal
Agent:  linked list rever
Agent: sal implementation
Agent:  for you.
🔧 Tool Call: ToolCall {
    id: ToolCallId(
        "tooluse_qV0FLzMtS4qi7MAJerLlyQ",
    ),
    title: "fsWrite",
    kind: Other,
    status: Pending,
    content: [],
    locations: [],
    raw_input: Some(
        Object {
            "__tool_use_purpose": String("Creating a Python file with minimal linked list reversal code"),
            "command": String("create"),
            "path": String("reverse_list.py"),
            "content": String("class ListNode:\n    def __init__(self, val=0, next=None):\n        self.val = val\n        self.next = next\n\ndef reverse_list(head):\n    prev = None\n    current = head\n    while current:\n        next_temp = current.next\n        current.next = prev\n        prev = current\n        current = next_temp\n    return prev"),
        },
    ),
    raw_output: None,
    meta: None,
}
Permission request from server: RequestPermissionRequest { session_id: SessionId("1c1f81d3-c2ce-464d-86b8-496403ad4da5"), tool_call: ToolCallUpdate { id: ToolCallId("tooluse_qV0FLzMtS4qi7MAJerLlyQ"), fields: ToolCallUpdateFields { kind: None, status: Some(Pending), title: Some("fsWrite"), content: None, locations: None, raw_input: Some(Object {"__tool_use_purpose": String("Creating a Python file with minimal linked list reversal code"), "command": String("create"), "path": String("reverse_list.py"), "content": String("class ListNode:\n    def __init__(self, val=0, next=None):\n        self.val = val\n        self.next = next\n\ndef reverse_list(head):\n    prev = None\n    current = head\n    while current:\n        next_temp = current.next\n        current.next = prev\n        prev = current\n        current = next_temp\n    return prev")}), raw_output: None }, meta: None }, options: [PermissionOption { id: PermissionOptionId("allow"), name: "Allow", kind: AllowOnce, meta: None }, PermissionOption { id: PermissionOptionId("deny"), name: "Deny", kind: RejectOnce, meta: None }], meta: None }
Agent: Done
Agent: ! I've created `reverse_list.py
Agent: ` with a minimal linked list reversal implementation.
Agent:  The `reverse_list` function takes
Agent:  the head of a linked list and returns the new
Agent:  head after reversing it using the standar
Agent: d three-pointer approach.
> ^C
~/Documents/Work/2025/Project/UI/amazon-q-developer-cli $ cat reverse_list.py 
class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next

def reverse_list(head):
    prev = None
    current = head
    while current:
        next_temp = current.next
        current.next = prev
        prev = current
        current = next_temp
    return prev~/Documents/Work/2025/Project/UI/amazon-q-developer-cli $ 

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