Add `Options` / `initial_options` validation

Suggestion raised in: https://github.com/slackapi/python-slack-sdk/issues/1509

Behavior:
initial_options options must contain an exact match of options provided, or users experience issues with properly updating forms. Suggestion has been raised to update this SDK to notify developers when an option provided does not exactly match an initial_options selection.

Category (place an x in each of the [ ])

• slack_sdk.web.WebClient (sync/async) (Web API client)
• slack_sdk.webhook.WebhookClient (sync/async) (Incoming Webhook, response_url sender)
• slack_sdk.models (UI component builders)
• slack_sdk.oauth (OAuth Flow Utilities)
• slack_sdk.socket_mode (Socket Mode client)
• slack_sdk.audit_logs (Audit Logs API client)
• slack_sdk.scim (SCIM API client)
• slack_sdk.rtm (RTM client)
• slack_sdk.signature (Request Signature Verifier)

Requirements

Please read the Contributing guidelines and Code of Conduct before creating this issue or pull request. By submitting, you are agreeing to those rules.

slack_sdk.models から始めて、Options と initial_options の UI コンポーネント定義を見つけてください。周辺のモデルの動作を読み、オプション値がどのように表現されているかを確認したうえで、完全一致のバリデーションを追加し、不一致が SDK ユーザーに報告されることを検証してください。