Implement Refresh Lifecycle Hooks

[niteshpurohit]

Feature Request

Description:

Provide lifecycle hooks (before_refresh, after_refresh) that can be configured to run before and after a materialized view is refreshed.

Use Case:

This allows developers to inject custom logic into the refresh process, such as logging to an audit trail, busting external caches, or triggering other downstream processes.

Proposed Solution:

• In the initializer, allow configuration of global before_refresh and after_refresh lambdas that receive the view definition as an argument.
• Allow these to be defined on a per-view basis as well, perhaps as serialized attributes on the model.
• The MatViewRefreshJob will execute these hooks at the appropriate times.

RSpec Tests:

• Configure a before_refresh hook that sets a flag.
• Run a refresh and verify the flag was set before the refresh SQL was executed.
• Configure an after_refresh hook.
• Run a successful refresh and a failed refresh, and verify the hook is called in both cases with the correct status.

Checklist:

• I have searched for a similar feature request and didn't find any duplicates.
• I have included all the required information.
• I have tagged the issue with the label "enhancement".

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