Add Pre-Update Callback Function Trigger to Parameter Update Process

[furushchev]

Hi! I want to propose a new feature for this great library!

This pull request adds a trigger point for a callback function right before any parameter value is updated.
This enhancement complements the existing functionality where a callback can be called after the parameter update.

Motivation

Some camera devices must stop streaming before changing settings and then restart it after the update.
This pre-update callback will provide users with the flexibility to programmatically handle such scenarios.

Changes

• Added setPreUpdateCallback / clearPreUpdateCallback
• Added setPostUpdateCallback (which is identical to the original setUserCallback)

Backward Compatibility

This change is fully backward compatible. (The original methods are kept as-is)
The new callback is optional and does not affect the existing workflow if not used.