Add tool filter to MCP support

[seratch]

Implement the feature equivalent to openai/openai-agents-python#861

[vrtnis]

hey @seratch ! - i gave this a go for your consideration following openai/openai-agents-python#861 .

pnpm -F mcp start:tool-filter will launch the new tool-filter-example.ts, and you’ll see the example tool get blocked in the output. happy to make any changes based on feedback!

[seratch]

Thanks for sending the PR! I will look into it tomorrow in my timezone