feat: add metadata entity transform for global value sets

[rossreicks]

Added Support for Global Value Sets in AddValueSetEntries Task

Description

Enhanced the AddValueSetEntries task to support Global Value Sets in addition to Standard Value Sets. This allows users to programmatically add new entries to Global Value Sets while maintaining existing functionality for Standard Value Sets.

Features

• Adds ability to create new entries in Global Value Sets
• Supports global entry fields including:
  • fullName
  • label
  • default
• Prevents duplicate entries (skips if entry already exists)
• Maintains consistent behavior with Standard Value Sets

Example Usage

task: add_global_value_set_entries
options:
     api_names: CustomValueSet__c
     entries:
            fullName: NewValue
            label: New Value Label
            default: true

Testing

Added comprehensive test suite covering:

• Basic entry addition
• Multiple entry handling
• Duplicate entry prevention
• Default value handling

Notes

This is my first PR to cumulus so, hello!

[salesforce-cla]

Thanks for the contribution! Before we can merge this, we need @rossreicks to sign the Salesforce Inc. Contributor License Agreement.