feat(CommandService): add command filtering configuration options

[TomorJM]

TLDR

This commit adds a new configuration option Settings to the CommandService, allowing command filtering based on core commands and excluded commands settings. Relevant tests and configuration patterns have also been updated.

Dive Deeper

In some use cases, for example, as an SRE installing qwen-code on a server terminal as a cli-agent (not for coding purposes), it is expected that when developers use this agent, the command usage scope can be more focused and manageable. For instance, the /bug command is not applicable in this scenario. Through configuration, you can selectively assemble commands when the cli is launched (applicable to built-in/MCP/file instructions).

Reviewer Test Plan

Example 1: Load only specific commands

{
  "coreCommands": ["help", "clear", "quit"]
}

Example 2: Exclude specific commands

{
  "excludeCommands": ["mcp", "extensions"]
}

Example 3: Combination (coreCommands takes priority)

{
  "coreCommands": ["help", "clear", "quit"],
  "excludeCommands": ["quit"]
}

In this case, only help and clear will be loaded since quit is excluded by the coreCommands filter.

Testing Matrix

This PR does not involve changes here.