[Neo Core Optimization] Organize core events.

[Jim8y]

Description

This pr defines interfaces for core event handlers. The reason of doing this is that the public event of the core is defined everywhere, and each of them has its specific parameters, making it hard to maintain. Thus having this pr to define all event handler interfaces together and added readme document to explain them.

Fixes # #3333

Type of change

• Optimization (the change is only an optimization)
• Style (the change is only a code style for better maintenance or standard purpose)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Run existing test

Test Configuration:

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[shargon]

Why the cast? we need to define in all the partial files the interface ILoggingHandler?

[Jim8y]

cause to make the method private, have to implement them implicitly, making it to be used this way.... Otherwise interface will be public.

[shargon]

Very similar name with ILoggingHandler

[Jim8y]

Cause they are defiend this way, one Log event one Logging event for different purpose.