feature(mvc.Collection): update collection methods

[jamesgeorgewilliams]

Description

Update mvc.Collection methods and relevant types.

Methods added:

• each
• filter
• includes
• isEmpty
• map
• reduce

Methods removed:

• pluck

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This PR fixes the mvc.Collection tests. The mvc.Events tests were copied to the mvc.collection.js test file by accident, so this just reverses that.

Around 14 instances of pluck were removed from the test file, and replaced with map. collection.pluck('id') => collection.map((model) => model.get('id'))

The PR also removes the instances of Array.from from mvc.Collection.

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The PR also fixes exposing extend and addMethodsUtil from mvcUtils to the user.

TODO:

• Add tests for methods
• Document methods