Adding SecretScanning Toolset

[tonytrg]

This PR adds:

• Secret Scanning Toolset
• List secret scanning alerts for a repository
  • I kept the optional params short to not overload the tooling
• Get a secret scanning alert

[Copilot]

Pull Request Overview

This PR introduces a new secret scanning toolset to the MCP server by adding two new commands: GetSecretScanningAlert and ListSecretScanningAlerts.

• Integrates secret scanning tools into the toolset initialization in pkg/github/tools.go.
• Implements secret scanning functionalities in pkg/github/secret_scanning.go with accompanying tests in pkg/github/secret_scanning_test.go.
• Updates the README.md with usage documentation for the new secret scanning endpoints.

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

File	Description
pkg/github/tools.go	Registers the secret scanning tools into the toolset collection.
pkg/github/secret_scanning_test.go	Provides tests ensuring correct behavior of the secret scanning tool handlers.
pkg/github/secret_scanning.go	Implements the GetSecretScanningAlert and ListSecretScanningAlerts functions.
README.md	Adds documentation detailing the usage of the new secret scanning tools.

[tonytrg]

Did a manual test run:

Can you list me all secret scanning alerts in github/repo that are resolved?

A: 
Query params
{
  "owner": "github",
  "repo": "repo",
  "state": "resolved"
}

[
... Returned list of secretalerts, all resolved
]

Alright give me github/repo alertnumber 196

A:
Query params
{
  "owner": "github",
  "repo": "repo",
  "alertNumber": 196
}

{"number":196,
...
}

[SamMorrowDrums]

I think this looks great, just a couple of small comments.

[tonytrg]

@SamMorrowDrums good eye for product names.

[SamMorrowDrums]

Great work Tony!