[Traffic Control] Introduce script to aid in configuration (#20693)

## Description 

A script to somewhat simplify the process of determining how to
configure TrafficController in cases where nodes are running behind
proxies or other infra. See usage comment in code for more context.

## Test plan 

```yaml
# after changing x-forwarded-for configuration to 0 and restarting sui-node on the host...
ubuntu@jnb-tnt-val-00:~$ journalctl -fu sui-node | ./config-traffic-control.sh "95.217.193.168"
x-forwarded-for contents: 95.217.193.168
Configuration:
  client-id-source:
    x-forwarded-for: 1
```

---

## Release notes

Check each box that your changes affect. If none of the boxes relate to
your changes, release notes aren't required.

For each box you select, include information after the relevant heading
that describes the impact of your changes that a user might notice and
any actions they must take to implement updates.

- [ ] Protocol: 
- [ ] Nodes (Validators and Full nodes): 
- [ ] Indexer: 
- [ ] JSON-RPC: 
- [ ] GraphQL: 
- [ ] CLI: 
- [ ] Rust SDK:
- [ ] REST API:

scripts/config-traffic-control.sh

@@ -0,0 +1,88 @@
+#!/usr/bin/env bash
+# Copyright (c) Mysten Labs, Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+usage() {
+    echo "Usage: $0 <search_string>"
+    echo
+    echo "Provides a recommended configuration for the client-id-source "
+    echo "field of the sui-node policy-config config for traffic controller."
+    echo "To use, do the following:"
+    echo
+    echo "1. Set the following sui-node config:"
+    echo
+    echo "  client-id-source:"
+    echo "    x-forwarded-for: 0"
+    echo
+    echo "2. Start the node"
+    echo "3. Run this script, piping sui-node logs to it and providing the known client IP address as an argument."
+    echo "4. The script will output the recommended configuration for the client-id-source field."
+    echo "5. Set the client-id-source field to the recommended configuration."
+    echo "6. Restart the node."
+    echo "7. The node will now use the recommended configuration for the client-id-source field."
+    echo
+    echo "NOTE: If the node is not running behind a proxy, this script will not yield any results."
+    echo "      In such a case, set the client-id-source field to the default value of 'socket-addr'."
+    echo
+    echo "Example 1: journalctl -fu sui-node | $0 1.2.3.4"
+    echo "Example 2: echo 'x-forwarded-for contents: [\"1.2.3.4\", \"5.6.7.8\", \"4.5.6.7\"]' | $0 1.2.3.4"
+}
+
+# Check for help flag
+if [ "$1" = "-h" ] || [ "$1" = "--help" ]; then
+    usage
+    exit 0
+fi
+
+# Check that a search string is provided
+if [ $# -ne 1 ]; then
+    usage
+    exit 1
+fi
+
+search="$1"
+
+while IFS= read -r line; do
+    # Check if the line matches the pattern for x-forwarded-for
+    # Using a regex with a capturing group to extract the contents inside the brackets.
+    if [[ $line =~ x-forwarded-for[[:space:]]+contents:[[:space:]]+\[(.*)\]\. ]]; then
+        inside_brackets="${BASH_REMATCH[1]}"
+
+        # Replace '", "' with newlines to split into multiple lines, then read into an array
+        IFS=$'\n' read -d '' -r -a items < <(echo "$inside_brackets" | sed 's/", "/\n/g')
+
+        # Strip any non-integer characters from start and end of each item
+        for i in "${!items[@]}"; do
+            items[$i]=$(echo "${items[$i]}" | sed 's/^[^0-9]*//; s/[^0-9]*$//')
+        done
+
+        # Store the entire array into a variable (space-separated)
+        contents_var="${items[@]}"
+
+        # Find the index of the search element
+        found_index=-1
+        for i in "${!items[@]}"; do
+            if [ "${items[$i]}" = "$search" ]; then
+                found_index=$i
+                break
+            fi
+        done
+
+        if [ $found_index -ge 0 ]; then
+            # Calculate how many elements come after the found element
+            elements_after=$(( ${#items[@]} - (found_index + 1) ))
+            result=$(( 1 + elements_after ))
+
+            # Print the contents array and the recommended configuration
+            echo "x-forwarded-for contents: $contents_var"
+            echo "Configuration:"
+            echo "  client-id-source:"
+            echo "    x-forwarded-for: $result"
+
+            exit 0
+        fi
+    fi
+done
+
+# If we get here, no match was found
+exit 1