mcp: add mcp method and tool logging to authorize (#5668)

## Summary

Adds support for extending authorization log with Model Context Protocol
details.

i.e. 
```json
{
  "level": "info",
  "server-name": "all",
  "service": "authorize",
  "mcp-method": "tools/call",
  "mcp-tool": "describe_table",
  "mcp-tool-parameters": { "table_name": "Categories" },
  "allow": true,
  "allow-why-true": ["email-ok", "mcp-tool-ok"],
  "deny": false,
  "deny-why-false": [],
  "time": "2025-06-24T17:40:41-04:00",
  "message": "authorize check"
}
```

## Related issues

Fixes
https://linear.app/pomerium/issue/ENG-2393/mcp-authorize-each-incoming-request-to-an-mcp-route

## User Explanation

<!-- How would you explain this change to the user? If this
change doesn't create any user-facing changes, you can leave
this blank. If filled out, add the `docs` label -->

## Checklist

- [x] reference any related issues
- [x] updated unit tests
- [x] add appropriate label (`enhancement`, `bug`, `breaking`,
`dependencies`, `ci`)
- [x] ready for review

authorize/evaluator/evaluator_test.go

@@ -689,8 +689,10 @@ func TestEvaluator(t *testing.T) {
 					URL:    "https://from.example.com",
 				},
 				MCP: RequestMCP{
-					Tool:   "tool_name",
 					Method: "tools/call",
+					ToolCall: &RequestMCPToolCall{
+						Name: "tool_name",
+					},
 				},
 			})
 			require.NoError(t, err)